It was a peace agreement between the British and Burmese in a Burmese village called yandaboo, near the capital Ava. The agreement was signed on 24 February 1826 by General Sir Archibald Campbell on the British side and by the governor of Legaing Maha Min Hla Kyaw Htin of the Burmese side. It is with this treaty that British rule begins in Assam. With British rule two areas developed, tea gardens and the crude oil sector, and many marginals, who came from time to time and settled in Assam. “The intervention of the british East India Company was carried out by a panel of experts trained by the Tea Committee (1834) to assess the scientific nature and commercial potential of Assam tea” (wikipedia.org/wiki/Assam_tea). On the other hand, the first production of oil began not only in India, but in Asia in 1889 in Assam near the city of Digboi. The fact is that during the construction of the Dibrugarh – Ledo Railway Line, oil leaks were observed near Digboi and crude oil was therefore discovered. To ensure livelihoods, many people came to Assam and settled. Moghul`s former rulers also tried to conquer Assam, but great Stalwartwies, such as Lachit Borphukan, thwarted their attempts. In this context, the Battle of Saraighat (a naval battle) fought in 1671 between the Mughal Empire (led by the King of Kachwaha Raja Ramsingh I) and the ruler of Ahom (led by Lachit Borphukan) on the Brahmaputra River near Saraighat, now Guwahati. In battle, Ahom`s army defeated the Mughal army through brilliant use of terrain and other tactics.
The Burmese, who had little choice, complained of peace. King Bagyidaw of Burma sent a delegation consisting of an American minister, an English minister and two Burmese ministers to meet with the commander of the British armed forces, General Sir Archibald Campbell.  The final negotiations were not negotiated at all. The Burmese had to accept all British requests. The British asked and the Burmese agreed: The first of the above five conditions led to the annexation of Assam to British India. Not only did this treaty end the most costly British war on Indian territory, but it also led, when the time came, to the end of Burma`s independence. It led to the end of the Third Burmese Empire (known as the Terror of British India). Burma was no longer a threat to the British on the eastern borders. The Yandabo Treaty was the peace treaty that ended the first Anglo-Burmese war.
… In accordance with the treaty, the Burmese accepted: Cede à la Brit-assam, Manipur, Rakhine (Arakan) and the Taninthayi coast (Tenasserim) south of the Salween River.