The vicissitudes of one leading family are treated as virtually synonymous with the emergence and extent of the land of Rus'. Yet in addressing the question of the origins of Rus', the chroniclers did not play fast and loose with facts. The Primary Chronicle registers actual political change and population movement under way in the late ninth century. In the mid-tenth century a Khazar ruler regarded the Severians, Slavs near the middle Dnieper, as owing him tribute, while Kiev had an alternative, apparently Khazar, name, Sambatas. It is significant that the politico-military locus of Rus' shifted south little more than a generation after northerners first arrived in force on the middle Dnieper. This registers the rapid development and allure of the 'Byzantine connection', in terms of trading and the wealth it could yield. Sometime in the mid-960s Sviatoslav forged an alliance with a group of nomads, the Oghuz, and launched a joint attack on the Khazars.