British annexation of Assam

The present-day state of Assam and its predecessor Undivided Assam was colonized by the East India Company and the British Raj over a period of 150 years—beginning with the Goalpara region in 1765 to drawing of the McMahon Line in 1913-1914 when the British consolidated its rule over the present-day Arunachal Pradesh.

1765–1824

James Rennell's 1776 map shows the eastern boundary of the British controlled regions before 1824

Following the Battle of Plassey (1757), the East India Company received the Diwani of Bengal in 1765 from the Mughals, and with it a major part of the Goalpara region. The northern part, called the eastern Duars were still with Bhutan.