They came to Mahanaim - So they returned to the place whence they set out. See 2 Samuel 2:12. This was the commencement of the civil wars between Israel and Judah, and properly the commencement of the division of the two kingdoms, through which both nations were deluged with blood.
Through the plain - See 1 Samuel 23:24. Bithron is unknown. From the expression all (the) Bithron, it seems likely that it is a tract of country, intersected by ravines lying on the east side of Jordan.