Birbhadra belonged to the prominent Bagale Thapa clan of Jumla that migrated eastwards as per Gorkha chronicles.

[2][3][4] However, the Sardari annual reinstatement letter of his youngest son Amar Singh Thapa (sanu) on Chaitra 1855 B.S.

His eldest son died in the Battle of Kantipur with powerful Kaji Kalu Pande.

[8] King Prithvi Narayan Shah's first military commander Shivaram Singh Basnyat was married to Sura Prabha, a sister of Bikram Thapa and an aunt of Birbhadra.

[9] Birbhadra, being a nephew of Shivaram Singh's wife Sura Prabha, was easily recruited into the minor ranks of Jamadar in the army of the Gorkha Kingdom.