[1] Khan was born on 11 February 1896 to an royal Bengali Shia family known as the Nawabs of Longla based in the village of Prithimpassa in South Sylhet (then under the North-East Frontier province of the British Raj).
The royal family are descended from Sakhi Salamat, a Persian nobleman from Greater Khorasan, who settled in Prithimpassa after being granted land there by the Lodi sultans of Delhi in the 15th century.
[2] The Assam Legislative Assembly was founded in 1937, and Khan won a seat in its first elections in the South Sylhet (East) constituency.
In 1945, he led his party into an alliance with Assam Congress and its coalition partners which included the likes of Bordoloi and Fakhruddin Ali Ahmed (who later became the President of India).
In 1950, he hosted King Mohammad Reza Pahlavi of Iran and Governor-General Khwaja Nazimuddin at his estate for four days and went hunting with them.