By 1734, the region of Bihar, which had existed as an independent subah (province) since the days of the Mughal emperor Akbar (r. 1556-1605), was incorporated into the larger and richer subah of Bengal to its east. It was to remain part of Bengal until 1912. However, while Bihar was absorbed within the boundaries of Bengal, it was never assimilated. Ironically, whereas Bengal had been thought of for long centuries since the thirteenth, and especially from the perspective of empires based in Delhi/Agra, as a frontier territory, now it was Bihar that came to assume that position from the perspective of the Bengal nawabs’ capital of Murshidabad (and under British colonial rule, from the perspective of Calcutta). This paper examines the important political and social effects of this making-into-a-periphery of a region otherwise located in the Gangetic heartland of northern India not only geographically but also in terms of its intimate and vital links with the western lands of ‘Hindustan’ through its religious traditions, pilgrimage circuits, its cultural orientations, its linguistic ties, its agrarian and trading networks and practices. Specifically, it investigates the consequences of this administrative subordination of Bihar to Bengal for the lineaments of agrarian, political and economic power as they affected social relations in the former. It discusses the relations between the provincial governors and jagirdars of the decentralizing Mughal Empire, local lords and the different layers of their subordinates, including cultivating groups, landless labourers and artisans. With the power of local lords stunted by the greater ones in Bengal, and the horizons of their political ambitions and growth circumscribed within these ‘borderlands’, this paper asks what the consequences were for the relations of patronage, protection and the reciprocal duty of service that had sustained dynamic relations of mutuality between dominant and subordinated groups within local communities in Bihar. It asks whether we can we already detect some of the signs of rigid and violently maintained caste hierarchies that are today identified with Bihar and that so frequently engender its characterization as a political, cultural and social ‘back-water’.