Why he came in
Abu’l Fazl frames it as pressure, not affection. Mewat had been assigned to Sharifu-d-din Husain Mirza, who moved on Amber, exacted a contribution, and took as hostages Jagannath, Raj Singh and Kangar — the Rajah’s son and two nephews. A rival claimant within the family, the son of Bihari Mal’s elder brother Puran Mal, had gone over to the Mirza and “raised troubles”.
The Akbarnama then has Bihari Mal introduced to Akbar by Chaghatai Khan, with his relations and the leading men of his clan, his eldest son Bhagwant Das excepted “as he had been left in charge of the families”. Blochmann records the outcome flatly: “Bihárí Mall was the first Rájpút that joined Akbar’s Court.”
The alliance, in the chronicler’s own framing
Abu’l Fazl presents the marriage as Bihari Mal’s initiative and as an escape from a class: the Rajah “considered that he should bring himself out of the ruck of landholders and make himself one of the distinguished ones of the Court. In order to effect this purpose he thought of a special alliance.”
What followed is recorded on p. 243 of Beveridge’s translation, at Sambhar. Blochmann adds the settlement: on reaching Agra, Bihari Mal was made a Commander of Five Thousand. Three of his sons served Akbar; his grandson would go further than any of them.