Charles Ellicott Commentary 1 Chronicles 10:7

"And when all the men of Israel that were in the valley saw that they fled, and that Saul and his sons were dead, they forsook their cities, and fled; and the Philistines came and dwelt in them." — 1 Chronicles 10:7 (ASV)

That were in the valley. —Rather, the plain, in which the main battle was fought—that of Jezreel. Samuel has that were on the other side of the plain, and on the other side of the Jordan. The concise phrase who (dwelt) in the plain, may be compared with 1 Chronicles 9:2. The people of the surrounding districts are meant. When they saw that they (namely, Saul’s army, identified in Samuel as the men of Israel) fled, or had been routed, they deserted their (in Samuel, the; perhaps a transposition of letters) cities, which were then occupied by the Philistines.

Dwelt in them. —The pronoun here is masculine. In Samuel, the pronoun is feminine, which is correct.