Burma, also spelled Birmah, was a coastal nation located east of Hindustan on the same continent, (TV: Survivors of the Flux) with Hindustan being located in southern Asia. (TV: War of the Sontarans)
Geography
Roughly south-east of Birmah was Siam and to the west was Hindoostan. The south-western coast of Birmah overlooked the Bay of Bengal. (TV: Survivors of the Flux)
History
In the 13th century, Burma was under the nominal control of Kublai Khan. The First Doctor once won all its commerce for one year by playing high-stakes backgammon. (TV: "Assassin at Peking")
Birmah appeared on a map of the region in 1904. (TV: Survivors of the Flux)
In November 1926, anti-British Empire protests took place in the Burmese city of Mandalay. The tigress Dawon's owner was killed in the protests. (AUDIO: The Emerald Tiger)
Behind the scences
In the real world, the country historically known as Birmah/Burma is also known as Myanmar, a name which has come to be preferred in modern sources. However, it has yet to be used in works relating to the Doctor Who universe.
Series 13 of Doctor Who was inconsistent on Birmah's location: the map shown in War of the Sontarans shows Hindustan to be in south Asia. On the map shown in Survivors of the Flux, Birmah is located east of Hindustan on the same continent.