Assam came under British control after the First Anglo-Burmese War through the:

Assam came under British control after the First Anglo-Burmese War (1824-1826), through the Treaty of Yandabo, signed on 24 February 1826.

Background:

• In the early 19th century, the Burmese (Konbaung dynasty) expanded their empire and conquered Arakan, Manipur and Assam.
• The Ahom kingdom of Assam had been weakened by internal conflicts, and the Burmese invaded it several times between 1817 and 1822.
• The Burmese advance brought them into conflict with the British on the borders of Bengal.

The First Anglo-Burmese War (1824-1826):

• War broke out in 1824, during the governor-generalship of Lord Amherst.
• The British sent forces by land and by sea, captured Rangoon, and advanced up the Irrawaddy river towards the Burmese capital, Ava.
• The Burmese general Maha Bandula was killed in 1825.
• The Burmese king agreed to peace.

The Treaty of Yandabo (1826):

• It was signed at Yandabo, a village near Ava (in present-day Myanmar).
• The Burmese gave up their claims over Assam, Manipur, Cachar and Jaintia.
• They ceded Arakan and Tenasserim (coastal Burma) to the British.
• They agreed to pay a war indemnity of one million pounds.
• They agreed to accept a British Resident at Ava.

Results for Assam:

• Assam was brought under British control; the British later annexed it fully (1838).
• The British developed tea plantations in Assam from the 1830s.
• Manipur was recognised as an independent state under British protection.

Later Anglo-Burmese Wars:

• Second (1852): Lower Burma (Pegu) annexed.
• Third (1885): Upper Burma annexed, under Lord Dufferin; Burma became a province of British India (1886).
• Burma was separated from India in 1937.

Why not the other options?

• ✗The Treaty of Sugauli was with Nepal.
• ✗The Treaty of Gandamak was with Afghanistan.
• ✗The Treaty of Salbai was with the Marathas.