By the late fifteenth century, medieval political, social and economic institutions in the older settled, coastal parts of the southern peninsula had been weakened and no longer were the model of society that the Vijayanagara state had ostensibly been created to defend. Tamil country was the major imperial frontier during the sixteenth century, the processes of change there are analysed in recent work of Karashima, Subbarayalu, and Ludden. Lordships in sixteenth-century Tirunelveli reflected the distribution of its varied peoples in Vijayanagara times. In mixed-cropping zones, including the greater part of the Vijayanagara heartland, the potential for reliable irrigation was achieved by tank reservoirs and wells. Mixed and dry-cropping zones contributed major commodities as cotton and indigo to the peninsular economy. During the Vijayanagara period the pace of commercialisation had quickened led by two factors: overseas trade and the deliberate policy of territorial magnates of augmenting their money revenues through customs fees.