Bereg, a grandson of Baran, was dissatisfied with Estolad, and so he in about FA 365 led a thousand men of the House of Bëor away southwards out of the Beleriand, disappearing from the histories. It is possible some of his descendants were the ancestors of the later Men of Eriador.
In the book Silmarillion, Galdweth (man) is told a story by Haldad about his childhood rival, Bereg of Bëor, after talking with him in a party arranged by Haleth of the House of Haleth, daughter of Haldad. In this conversation, Galdweth calls Bereg the name he used in his childhood, Hardur. Bereg replies by saying that he has finally reclaimed the name of Bereg of Bëor (also called Prince), grandson of Baran. Bereg reclaims then Haleth as his wife (Galdweth had a crush on Haleth).
Bereg was the youngest prince of the Edain, Baran's heir of the great western lands, Estolad.
The true father of Bereg died in the battlefield few years after his birth leaving his wife and Bereg under Baran's treatment, but he ignored them and sent them to a little village in the north of Balan without any reason at all. Then, Baran died of old age and his fortune was given to his many sons and grandsons, including Bereg.
Now the powerful Bereg was looking for a deal between the House of Bëor and Haldad's family. This deal included the marriage. Bereg eventually dissatisfied with Estolad, led part of the people away to unknown lands, disappearing from the history.