Charles Ellicott Commentary 2 Samuel 19:40

"So the king went over to Gilgal, and Chimham went over with him: and all the people of Judah brought the king over, and also half the people of Israel." — 2 Samuel 19:40 (ASV)

All the people. —The tribe of Judah, deeply moved by the measures and words of David, had united generally in his restoration; the other tribes, who had first proposed to return to their allegiance (2 Samuel 19:9–10), had not had time to join in the present movement, or had not generally known of it. Only Shimei with his one thousand Benjamites, and doubtless others living near, together with the tribes east of the Jordan—represented altogether as half the people of Israel—were able to come together.