At the time of British rule in Burma the Tai Yai people were the majority of the population in Kengtung state with other groups such as Akha and Lahu, forming sizeable communities.

[6][7] Despite the ethnic affinity of the ruling Tai with the Siamese to the south,[8] Kengtung was led by Saopha princes who historically preferred to pay tribute to the Burmese kings to the west.

The King of Mandalay restricted himself to exacting a yearly tribute, often in the form of offerings of ritual gold flowers, leaving the Kengtung rulers largely alone.

In 1760, following conflicting claims of political influence over Kengtung State, there was a war between the Qianlong Emperor of the Qing Dynasty and the King of Burma, Hsinbyushin.

[4] During British rule in Burma the eastern border was demarcated by the colonial powers and the western part of Kengcheng was merged with Kengtung.

The annexation of the trans-Salween territories historically claimed by Thailand was formalised on 1 August 1943 and the northern province of Saharat Thai Doem was established.

[14] Thailand left the territory in 1945, but officially relinquished its claim over Kengtung State only in 1946 as part of the condition for admission to the United Nations and the withdrawal of all wartime sanctions for having sided with the Axis powers.