Amar Singh started out as a normal military officer for Brahmachal (Southern Sylhet) ruled by Raja Jayananda. Jayananda had two sons, Srinanda the elder and Upananda the younger. Singh conspired against the elder brother from taking the throne by taking advantage of Srinanda's chronic rheumatism. He was able to get Upananda to join his side. Srinanda protested against this proposal but was unsuccessful and fled to Kamrup where he became a sannyasi of Kamakhya Temple, leaving behind his wife and son. With the acceptance of the royal officers, Upananda became the king of Brahmachal and subsequently Amar Singh became the chief military general.
