 The population of Eastern Bengal and Assam was 30,961,459 in 1901.The densely populated districts in East Bengal and the Surma and Brahmaputra Valleys were home to Indo-Aryan ethnic groups, including the Bengalis (27,272,895) and the Assamese (1,349,784).Hill districts were home to a predominantly Tibeto-Burman population, including groups like the Chakmas, Mizos, Nagas, Garos and Bodos.