This study is a richly detailed historical work of the unsettled half-century from the 1790s to the 1830s when the British East India Company strove to establish control of the colonial north-eastern frontiers spanning the River Brahmaputra to the Burmese border. It offers a much-needed reframing of regional histories of South Asia away from the subcontinental Indian mainland to the varied social ecologies of Sylhet, Cachar, Manipur, Jaintia, and Khasi hills. As a mercantile corporation, the EIC aimed at getting in command of the millennium-old over-land commercial routes connecting India and China. The study specifically engages with the early nineteenth century explorations of trade across Burma. Simultaneously, the Mughal diwani grant compelled the EIC to govern territory. Drawing on extensive research, the study demonstrates the incompatibility of bureaucratic power, the complex socio-economic networks of authority, and the ever-changing landscapes of the region. In a monsoon climate, where rivers moved and land was inundated for months, any attempt to form a uniform administration tended to clash with hybrid landscapes and waterscapes. This work explores how daily administrative and military practice shaped colonial polities and subject formation. Located at the intersection of colonial, legal, and environmental history, the study is of particular interest for scholars and students in history, political ecology, and anthropology.