Borin was born in 2450. He was the son of Nain II and brother of
Dain I. He had a son named Farin and was the great-great grandfather of
Most of the folk of Durin
left the Grey Mountains after Dain I was slain by a great
cold-drake. Borin accompanied Thror, Dain’s heir, to Erebor,
where they became prosperous and lived well. Borin died in 2711.
Reference: Appendix of Lord
of the Rings