जाइपराजिओ खलु कासी णियाणं तु हत्थिणपुरिम्म । चुलणीए बंभदत्तो, उववण्णो पउमगुम्माओ ॥१॥
Indeed, Brahmdatt — having died in Kashi and having made a death-wish (niyāna) — was born in Hastinapura in the house of Queen Chulani, from a lotus cluster (padmagulma).
The chapter opens mid-story: Brahmdatt, the world-emperor, is not a random birth. He is the soul of Sambhut, who made a niyāna — a wish or intention made at the moment of death — in Kashi. The niyāna locked his rebirth trajectory. He was born to Queen Chulani of Hastinapura and became Brahmdatt, the Chakravarti. The word "paumagulma" (lotus cluster) describes the manner of his divine birth, marking him as extraordinary from the first moment.
The simple version: Brahmdatt — previously Sambhut — made a wish at death in Kashi and was reborn as the world-emperor of Hastinapura. His ambition from a past life became his present-life destiny.