During the reigns of Jahangir (AD 1605-1627) and Shah Jahan (1627-658) the Tai (Shan)-speaking Ahom had prevented Mughal incursion into Assam, to the east of India. In 1662 Mir Jumla, Governor of Bengal, attempted to take Assam for the Mughals. The invading army suffered great losses and within four years the Ahom had regained all their territory. In 1793 the British entered into a trading relationship with the Ahom monarch of Assam.

By the end of the 18th century the main revenue funding the East India Company came not from trade but from indemnities, tribute and taxes from Indian states. This meant that annexation of new territories, though expensive, was attractive. In 1824 the First Burmese War was declared to fight back Burmese incursions into Assam. The Burmese were repelled and between 1826 and 1838 Assam was gradually brought under British control. The British promoted tea-growing and other commercial enterprises in the region. They improved the infrastructure and built railways so facilitating revenue extraction. During the Great Rebellion (Indian Mutiny) in 1857 Banda, the Raja of Assam, risked trying to incite the 1st Assam Light Infantry to join the rebellion. He was arrested and exiled.