Neolithic pathways in East Asia: early sedentism on the Mongolian Plateau

Abstract

The shift to sedentary lifeways represents a significant change in human adaptation. Despite the broadly contemporaneous timing of this transition across East Asia during the Holocene Climatic Optimum, such changes varied regionally. This article synthesises new and existing data from Neolithic sites on the Mongolian Plateau to reveal a simultaneous shift towards investment in site architecture, with distinct variation in the organisation of settlement and subsistence across biogeographic zones. The development of sedentary communities here emphasises the importance of climatic amelioration for incipient sedentism, and demonstrates how differences in ecological and cultural contexts can encourage various responses to the same environmental stimuli.

Introduction

Human adaptation to northern climates is distinct from other world regions, particularly in terms of sedentism and domestication. Following the Last Glacial Maximum, northern latitudes are often characterised by the persistence of hunting and gathering, and a specific range of organisational changes, including an early and protracted reduction in residential mobility, an intensified exploitation of aquatic species and more active management of natural resources. Across the global north (broadly, North America and Eurasia north of 40°), these shifts occurred at different times following the Last Glacial Maximum, and were closely tied to climatic amelioration (Gamble 1986; Elston et al. 2014; Popov et al. 2014; Liu et al. 2015a; Janz 2016). Depending on the region, such changes preceded a range of further organisational shifts, including a return to greater mobility, the adoption of exotic domesticates and increasingly specialised hunting strategies (Basgall 1987; Beck & Jones 1997; Fisher 2002; Wolff 2008; Weber & Bettinger 2010; Bousman & Okasnen 2012; Chatters et al. 2012; Rosenthal & Fitzgerald 2012; Habu 2014; Popov et al. 2014). In the northern latitudes, subsistence was characterised by the continued management of local resources, with little emphasis on domestic crops or animals. Furthermore, the adoption of exotic domesticates occurred long after they were adopted in neighbouring regions (e.g. Ames 1998; Crawford 2011; Popov et al. 2019; Janz et al. 2020). Hence, in contrast to the situation in Western Eurasia, in North-east Asia, the ‘Neolithic’ was characterised by a series of shifts that did not always result in long-term sedentism or domestication.

The Mongolian Plateau is a critical but poorly understood region in East Asian prehistory. Scholars have been inclined to assume that, throughout prehistory, people on the plateau have persistently retained highly mobile lifeways, initially based on hunting and culminating in nomadic pastoralism; this interpretation stems from the historic narrative of ‘steppe nomadism’ and the absence of concentrated and productive r-selected resources (i.e. species with high reproductive potential, such as fish, shellfish and nuts) (Cao 2007). Such supposition, however, is now challenged by archaeological data from the eastern Plateau indicating more sedentary lifeways and intensified exploitation of local resources after 8.5 ka cal BP (Zhao 2020). This general reduction in residential mobility was supported by diverse subsistence strategies, including grain cultivation, broad-spectrum foraging and the intensive exploitation of large game. The juxtaposition of these various modes of subsistence is emphasised by their association with climatic amelioration, raising questions about the common drivers of change.

Geographically, the eastern Mongolian Plateau is bounded to the east by the Great Khingan Range, with ecozones today ranging from arid or semi-arid steppe to the semi-humid margins of north China and the north-east China Plain (Ren 1999). Notable variations in modes of subsistence across the region reveal the diversity of adaptations to sedentary life in monsoon-dominated East Asia during the Holocene Climatic Optimum (c. 8.3–5.5 cal BP (Herzschuh 2006: 167)). An examination of Neolithic subsistence and settlement patterns on the eastern Mongolian Plateau presents the opportunity to explore these variable trajectories in sedentism, including their limits in regions with low rainfall and extreme seasonal variation.

The sites of Baiyinchanghan, Hag and Tamsagbulag represent sedentary adaptations within three distinct micro-environmental zones of the eastern Mongolia Plateau: the transitional zone between steppe and deciduous forest, the resource-rich wetland zone and open steppe. Baiyinchanghan (Figure 1.1) is located on the upper West Liao River valley, in the southernmost part of the study area (Neimenggu 2004). The primary phase of occupation, dating to 8034–7325 cal BP (Table S1 in the online supplementary material (OSM)), is associated with the Xinglongwa Culture. Baiyinchanghan is one of the most westerly Xinglongwa sites to be extensively excavated and reported in the Chinese literature (Liu 2001). The site represents the westward expansion of early millet-based agricultural economies in north-east China. Hag (Figure 1.2) dates to 8580–8036 cal BP (Table S1) and is located on the Hulunbuir Steppe far in the north of the study area. The Hailar, a tributary of the Amur (Heilongjiang) River, surrounds the site on three sides (Zhongguo et al. 2010). Dating to 8400–7339 cal BP (Table S1), Tamsagbulag (Figure 1.3) is located along tributaries of the Hulunbuir drainage system, a few hundred kilometres west of Hag. The upper West Liao River valley and the Hulunbuir Steppe are located on the margins of regions categorised by the Köppen-Geiger climate classification as cold semi-arid (BSk) and boreal winter dry with a cool to warm summer (Dwc to Dwb) (Beck et al. 2018). (The Köppen-Geiger climate classification system categorises all world climates according to seasonal temperature and precipitation patterns, and is one of the most widely used climate classification systems; B = arid, S = steppe/semi-arid, k = cold arid; D = boreal/snow, w = winter dry, c = cool summer, b = warm summer; http://koeppen-geiger.vu-wien.ac.at/.) Modern average annual precipitation at Tamsagbulag is 190mm, compared with 350mm at Baiyinchanghan. The Hulunbuir Steppe is colder than the West Liao River valley, with shorter growing seasons (Wu et al. 2015). Here, we examine similarities and differences in subsistence, site structure and material culture to identify variation in patterns of residential stability within some of the more marginal reaches of mainland East Asia.

Figure 1. Geographic location of sites mentioned in text and online supplementary material (OSM) (GMTED 2010, image courtesy of the U.S. Geological Survey).

Trajectories in sedentism

Site architecture

All three sites reveal significant investment in architecture that is consistent with full or intensive seasonal sedentism. Hulunbuir sites are characterised by large, 40–50m² dwellings, with carefully constructed roofs, floors, and indoor middens and/or storage pits (Figure 2) (Okladnikov & Derevianko 1970; Dorj 1971; Zhongguo et al. 2010). Evidence of surface dwellings at Tamsagbulag, within 1km of pit dwelling concentrations, suggest some form of year-round occupation (see the OSM). At the Hag site, a layer of shells more than 0.16m thick was found beneath the living floor, and may have served to keep the floors dry and provide insulation (Zhongguo et al. 2010).

Figure 2. A) The excavation zone at the Hag site: F = house; H = midden or storage pit; D = posthole; M = burial; SHD = piles of sand; JS3 = piles of animal bones. All remains belong to cultural layer 7 (after Zhongguo et al. 2010: foldout page); B) house 1 from Tamsagbulag, showing postholes, pit features, and hearth. The circular feature on the northern wall is a human burial (redrawn from Okladnikov & Derevianko 1970: 5).

Excavations at Baiyinchanghan have revealed contemporaneous, or slightly later (Table S1), evidence for intensively planned population nucleation, characterised by two settlement clusters on the hillslope—each with its own associated hilltop cemetery (Figure 3). Excavation has revealed 56 rectangular, semi-subterranean houses arranged in neat rows within the two clusters. Many of the houses had living floors that were typically surfaced with fired clay for durability (Neimenggu 2004). Extensive trench features at Baiyinchanghan and Tamsagbulag (see the OSM) and the elaborate floors at Hag and Baiyinchanghan illustrate investment in place that is uncharacteristic of earlier periods.

Figure 3. A) Layout of Xinglongwa-period houses at Baiyinchanghan (H = midden or storage pit) (redrawn from Neimenggu 2004: foldout page); B) the plane and section view of house AF32 of the Baiyinchanghan site (1, 3, 6, 8 = stone rollers; 2 = pestle; 4 = handstone; 5 = rock; 7 = perforated stone disk; 9 = cylinder jar) (after Neimenggu 2004: 145).

Differences in burial ritual between Baiyinchanghan and the two Hulunbuir sites similarly highlight contrasting levels of site investment. The Baiyinchanghan burials are represented by individual pit-tombs capped with layers of stone (Figure 4C). Some tombs have vertical stone slabs lining the walls (Neimenggu 2004). In contrast, the Hag and Tamsagbulag burials are scattered and unmarked (Figure 4A–B), including one subfloor interment at Tamsagbulag (Dorj 1971). Graves at Hag are often characterised by secondary inhumations (Zhongguo et al. 2010). The pattern of elaborate inhumation and structured community burial at Baiyinchanghan is characteristic of planned investment in recurrent and intensive site use. In contrast, across Hulunbuir, the diverse approaches to burial, the consistent lack of surface markings and evidence of secondary interment (e.g. at Hag) are more consistent with a less organised—or perhaps discontinuous—site usage.

Figure 4. A) Hag burial 04 07T5-T6XM3 (after Zhongguo et al. 2010: 32); B) Tamsagbulag burial from house 1 (redrawn from Okladnikov & Derevianko 1970: 9); C) Baiyinchanghan burial M13 (after Neimenggu 2004: 29).

The subsistence basis of ‘sedentism’

Sedentism requires sufficient resources within the catchment zone and highly efficient methods of exploiting them. Without improved procurement strategies, people must relocate during the year in order to avoid local resource depletion (Kelly 1983). The use of storage pits at all three sites (see the OSM; Figures 2–3) highlights the fact that increased sedentism—particularly in northern climates—requires more abundant seasonal procurement for storage. Although sedentism was once assumed to be dependent upon farming, we now know that sedentism can be supported without agriculture through the intensive exploitation of wild species that occur in dense concentrations and are resilient to harvesting pressure, such as fish, shellfish, nuts and seeds (Henry 1985; Gamble 1986; Rosenswig 2006; Habu 2014; Popov et al. 2014). While the three sites in this study have yielded evidence for the exploitation of such species, it varies greatly across sites and does not necessarily correlate with the apparent degree of sedentism.

Pottery and milling stones are present at the three sites (Figures 5–7). Despite their ubiquity in agricultural communities, such tools have been widely used by hunter-gatherers for cooking, shelling, grinding and pulverising many types of wild or domesticated plants (Adams 2013; Dubreuil et al. 2015). As such, their presence indicates a more intensive approach to plant exploitation, although not necessarily agriculture. Residue analysis from Baiyinchanghan and other Xinglongwa-phase sites indicates the exploitation of a wide range of wild species, including nuts, roots, rhizome bulbs and grasses (Tao et al. 2011; Wu 2014; Liu et al. 2015b). The quantity and formality of milling stone assemblages may indicate the relative importance of plant foods, and there is a clear regional divergence in the importance of these tools. The small, fragmented assemblages of grinding slabs and ball-headed rollers from Tamsagbulag and Hag (Figure 6), for example, contrast sharply with Baiyinchanghan (Table S2). Their absence from earlier sites on the Mongolian Plateau (Janz et al. 2017), however, emphasises the relationship between reduced mobility and increased investment in plant processing (Table S2).

Figure 5. Selection of lithics from Baiyinchanghan (after Neimenggu 2004: 289, 292, 294, 300, 301 & 303): A) grinding slab; B) digging weight; C) polished axe; D) handstone; E) pestle; F) hoe; G–H) flake tools; I) microblade core.

Figure 6. Selection of lithics from Hag (line drawings, all after Zhongguo et al. 2010: 35, 62, 64 & 71) and Tamsagbulag (photographs by L. Janz): A) grinding slab; B) digging weight; C) drill; D) projectile point (biface); E) microblade core; F) thumbnail scraper; G) retouched microblade tools; H) chipped adze; I) tongue-shaped scraper; J) fragment of ball-headed roller similar to those from Tamsagbulag.

Figure 7. A (top row): selection of pottery from Baiyinchanghan (after Neimenggu 2004: 278, 283 & 286); B (bottom two rows): selection of pottery from Hag (line drawings, all after Zhongguo et al. 2010: 75 & 83), and Tamsagbulag (photographs by L. Janz).

Aside from the exploitation of wild plant resources, millet-based farming also provided supplementary foods for the Baiyinchanghan communities. As no systematic flotation or bone chemistry studies have yet been published, we are unable to evaluate the dietary contribution of domesticated millets. Nonetheless, the presence and type of farming-related tools provide important clues to the scale and extent of the development of the farming. While Baiyinchanghan yielded no typical tools for harvesting (e.g. perforated knives) and ploughing (e.g. pointed spade-like tools), stone hoes comprise nearly 28 per cent of the entire lithic assemblage (Yang 2016). The lack of specialised harvesting and ploughing tools may suggest that cultivation was less intensive at Baiyinchanghan than at other contemporaneous sites in the heartland of north China, such as Cishan and Peiligang (Zhongguo 2010), although it could also indicate variation in agricultural practices. All Xinglongwa-period sites, including Baiyinchanghan, contain large quantities of wild faunal remains, and those with evidence of plant use likewise demonstrate the continued importance of wild resources (Liu et al. 2015a).

Hoes and spades are rare or absent in Hulunbuir. The numerous digging weights found at Tamsagbulag were probably used to build the pit dwellings and trench features (Figure 6). The relative lack of plant-processing tools at Tamsagbulag and Hag suggests that heavily processed plant resources were less important than at Baiyinchanghan. Higher densities of faunal remains at the Hulunbuir sites, combined with an emphasis on microblade- and projectile-based hunting technology, further suggest the greater relative importance of game over plant foods.

Direct evidence of diet is present in the sites’ faunal assemblages, with the range of animals being highly divergent across sites. Published species lists are available for Baiyinchanghan and Hag (Table 1), while analysis of the Tamsagbulag fauna is ongoing. Cervids represent the primary source of meat at Baiyinchanghan, while smaller prey was limited to a single fox (Vulpes sp.) element (percentage number of identified species (NISP) = 0.3). None of the animals were identified as domesticated. A broader range of species were exploited at Hag and Tamsagbulag. The latter site is characterised by an emphasis on aurochs (Bos primigenius), equids (Equus hemionus hemionus and Equus ferus) and antelope (cf. Saiga tatarica mongolica, Gazella subgutturosa and/or Procapra gutturosa), compared to the predominance of small prey (e.g. fox, birds, fish) and roe deer (Capreolus pygargus) at Hag.

Table 1. Comparison of faunal remains from Xinglongwa-period Baiyinchanghan and layer 7 of Hag (Neimenggu 2004; Zhongguo et al. 2010).

Aurochs dominate the Tamsagbulag assemblage; four such skeletons were recovered from the upper layers of one dwelling (Dorj 1971). Moreover, what appear to be ritual burials were recovered from contemporaneous sites near the city of Choibalsan, about 400km west of Tamsagbulag, including an aurochs bull skull and a cache of horns (Dorj 1971). Scholars have previously interpreted these sites as belonging to agropastoralists (Derevianko & Dorj 1992). The exploitation of small-bodied prey at Hag differs from Tamsagbulag, and presents the broadest spectrum of dietary species of the three sites analysed here, with a focus on riverine resources and terrestrial species that thrive around shrubby, riparian wetlands. These differences correspond to the local environment: Tamsagbulag sits high above a river, on the edge of an open steppe, whereas Hag is surrounded on three sides by a river. These trends might also be temporal, as Hag pre-dates Tamsagbulag.

Both Baiyinchanghan and Tamsagbulag exhibit higher levels of dietary specialisation than the earlier Hag site, although the emphasis varies greatly. The intensive exploitation of deer at Baiyinchanghan supports the notion of high occupational permanency, as cervids are resilient to heavy predation and are well adapted to forage on plants associated with high human population densities—particularly agricultural crops (Butler & Campbell 2004). In contrast, important species at Tamsagbulag, such as antelope and khulan (Equus hemionus hemionus), decline relative to human population density (Kaczensky et al. 2011). The unique juxtaposition of seemingly high levels of sedentism and an emphasis on wary large game at Tamsagbulag suggests that inhabitants practised a distinct approach to settlement and resource use.

The evidence presented here demonstrates high variation in levels of sedentism across the Mongolian Plateau during the Middle Holocene. The two Hulunbuir sites clearly reveal increasing sedentism and the coalescence of small hunter-gatherer communities, whereas the organisation of Xinglongwa-period site architecture and infrastructure at Baiyinchanghan supports the idea of a permanent village settlement. The pattern of differentiated dwelling types at Tamsagbulag suggests that the pit dwellings were designed for cold-season sedentism, while the surface dwellings were used during the warmer months (see the OSM). Together, these regions exemplify a large-scale trend, although with different approaches, towards increasing sedentism across North-east Asia.

Discussion

Holocene climatic amelioration and the onset of sedentism

The close temporal association of increasing and widespread sedentism across monsoonal East Asia and the Holocene Climatic Optimum—when annual average temperatures peaked and the East Asian Summer Monsoon strengthened and reached its northernmost limits—is compelling (Figure 8) (Winkler & Wang 1993; Dykoski et al. 2005; Herzschuh 2006). Multiple lines of evidence from lacustrine sediments along the south-eastern edge of the Mongolian Plateau show peaks in effective moisture between c. 8.0 and 4.0 ka cal BP (Liu et al. 2015c: 200; Fan et al. 2017; Wen et al. 2017). Proxy data from Lake Hulun, immediately west of Hag (Figure 1), indicate high lake levels between 11.1 and 6.2 ka cal BP (Zhai et al. 2011), with a marked shift c. 8.0 ka cal BP from dry steppe to relatively wet meadow-steppe, and the expansion of birch (Betula) and hazel (Corylus). This pattern lasted until c. 6.4 ka cal BP (Wen et al. 2010), when large Hulunbuir sites had already been abandoned or were in decline. As seen from Russian excavations farther east, in the middle and lower sections of the nearby Amur River basin (Popov et al. 2014; Tabarev 2014) and in Japan (Pearson 2006; Habu 2014), initial trajectories towards sedentism corresponded with phases of climatic amelioration, and, on the Mongolian Plateau, with peaks in maximum humidity between 8.0 and 7.0 ka cal BP.

Figure 8. Timing of Holocene Climatic Optimum compared to sites in this study; climate curve based on stalagmite δ¹⁸O records for Dongge Cave (after Dykoski et al. 2005).

These dates suggest that the trend towards sedentism was probably facilitated by ecological changes associated with the Holocene Climatic Optimum. Environmental conditions were arguably the primary driver of major contemporaneous shifts in settlement and subsistence patterns on the Mongolian Plateau, and probably across North-east Asia (Popov et al. 2014; Janz 2016; Shelach-Lavi et al. 2019). These ecological changes differed from region to region. In the West Liao River valley, the expansion of deciduous forests would have enhanced access to nut-bearing trees, while longer growing seasons and higher annual precipitation would have expanded the limits for producing large-seeded grasses, such as millets. The expanding wetlands, forests and meadow-steppe in Hulunbuir would have created richer habitats for all prey types—a process also witnessed in even more arid reaches of the western Mongolian Plateau (Janz 2016; Janz et al. 2017).

The role of the environment in adaptation

The eastern Mongolian Plateau sites discussed here contrast with regions typically discussed in similar studies, which show that the changes expressed in Middle Holocene sites neither persisted nor developed into fully sedentary lifeways. It is hypothesised that increasing aridity stimulated a rise in residential mobility across Late Neolithic Mongolia (Cybiktarov 2002; Chen 2011). At Tamsagbulag, the main occupation was abandoned after c. 7300 cal BP, and recent unpublished survey and excavation data from eastern Mongolia suggest a decline in occupational intensity after 6500 cal BP. After the adoption of nomadic pastoralism by 3.5 ka cal BP (Tumen et al. 2014; Honeychurch 2015; Wright et al. 2019), herding economies dominated much of the region into historic times. This explains the relative lack of cultural material in the upper stratigraphy at Hag (2.0–0.9 ka cal BP). These layers contain little evidence for house structures and a much lower artefact density, suggesting shorter occupation durations and less extensive site use. Although house structures and farming tools were still present in the later Neolithic at Baiyinchanghan, the site was abandoned during the Bronze Age, and no sedentary settlements have been found in the surrounding area from that time through most of the historic period (2.8–0.1 ka cal BP).

This discontinuity in the development of sedentary lifeways contrasts with trends in more temperate, less arid regions of East Asia (see Shi 1989). The trajectory of intensified farming and more entrenched sedentism continued among communities to the south, such as in the Yellow River valley, where seasonality was less extreme and precipitation more reliable (Zhongguo 2010). In temperate Japan, sedentism developed even earlier than on the mainland, and although it was not uniform and unilinear, residential stability was largely retained, and became tied to intensive resource management and aquatic resource exploitation that continued even after the introduction of crop agriculture after 800 BC (Akazawa 1986; Crawford 2011; Habu 2014). To a certain extent, this confirms the assumption that people living in cold, arid climates are more sensitive to climatic fluctuations and, in response to such fluctuations, make major changes in subsistence strategies. The emphasis on ungulate prey—from specialised exploitation of aurochs at Tamsagbulag to the persistent and widespread reliance on domesticated herd animals—further highlights the critical importance of large-game exploitation for subsistence in northern, continental climates.

Simultaneously, despite the fact that variability in the degree of sedentism and population density between regions are closely tied to differences in resource availability, it is difficult to determine the relative importance of environment vs cultural influences, particularly when there are clear, large-scale consistencies in site structure and material culture across a range of environmental contexts. The subsistence practices employed at Baiyinchanghan show no fundamental differences to those practised by other Xinglongwa communities located within milder climate zones to the east, such as Chahai and Xinglonggou (Liaoning 2012; Wu 2014). The pattern is also consistent with contemporaneous sites to the south, where the intensive exploitation of diverse plant resources included, but was not limited to, millet (Sun 2015; Chen & Yu 2017). Despite stark differences in topography and vegetation, Hulunbuir sites bear some resemblance to hunter-gatherer sites around Lake Baikal and the Amur River Basin, including: broad-spectrum foraging and the exploitation of aquatic resources; the persistence of rectangular pit dwellings exemplified at Tamsagbulag and earlier Neolithic sites in the Amur River basin; emphasis on microblade technology; and the practice of secondary burials (Derevianko & Powers 1969; Lbova et al. 2008). The data presented here highlight the importance and potential of untangling the complexities of environmental and cultural influences on sedentism and associated subsistence practices.

Conclusion

Globally, researchers increasingly recognise that climatic amelioration corresponds with trends towards increased dietary breadth, sedentism and domestication (e.g. Gamble 1986; Pearson 2006; Liu & Chen 2012; Zeder 2012; Elston et al. 2014; Janz 2016; Piperno 2011; Shelach-Lavi et al. 2019). Janz (2016) argues that these changes occurred globally during the Holocene and were closely tied to the creation of highly concentrated and diverse biotic patches. These resulted from wetland expansion and unprecedented forestation, due to the combination of higher humidity, megafaunal extinctions and increased atmospheric CO₂. Other researchers have emphasised the importance of land-use management strategies as a feedback mechanism in increasing resource abundance in the context of emerging sedentism (e.g. Yen 1989; Smith 2001; Crawford 2011).

The variation in prehistoric subsistence strategies across the eastern Mongolian Plateau is striking, and includes broad-spectrum hunting, the intensive exploitation of large game and high investment in plant use, supplemented by resilient, medium-sized game species. Our data show that in relation to sedentism, exploited resources may vary widely, even within close geographic regions. Furthermore, large- and medium-bodied prey may be more critical to sedentary lifeways in some regions than previously acknowledged. The emphasis on aurochs and equids at Tamsagbulag is surprising, given that large game populations typically decline around settlements (Jerozolimski & Peres 2003; Badenhorst & Driver 2009; Broughton et al. 2010; Schollmeyer & Driver 2013). Additional research on species composition, the extent and nature of plant use, population density and occupation duration in regions such as Hulunbuir will be critical in further illuminating the relationship between sedentism and exploitation of large game, particularly in northern regions.

The establishment of sedentary communities and semi-permanent dwelling structures represents a remarkable change in human adaptive strategies. This study shows that despite being relatively simultaneous, such changes were highly variable in character, even within individual regions. Such changes in residential mobility and dietary breadth occurred across North-east Asia as lake levels increased, wetlands expanded and deciduous and mixed forests fragmented the Pleistocene steppe ecosystems. Similar types of responses to climate change across a range of environmental conditions support existing hypotheses that greater dietary breadth and reduced mobility are tied to ecological change, while the resulting variations in site organisation and material culture derives from local, culturally mediated solutions to environmental stimuli. Even in communities vulnerable to climate change, culture plays an important role in recognising, selecting and implementing solutions. Likewise, broad similarities in material culture, settlement planning and burial practice across the region emphasise points of cohesion in mediating adaptation. As such, there is still potential in the traditional analysis of material culture for tracing cultural interaction and affiliation. Environmental transition zones, such as the eastern Mongolian Plateau, offer a testing ground where we can trace long-term trends in human responses to ecological change and culturally mediated adaptation.