Charles Ellicott Commentary 1 Chronicles 4:38-39

"these mentioned by name were princes in their families: and their fathers` houses increased greatly. And they went to the entrance of Gedor, even unto the east side of the valley, to seek pasture for their flocks." — 1 Chronicles 4:38-39 (ASV)

These mentioned by their names. —Literally, these who have come (forward) with names, that is, they have been adduced by name.

Were princes in their families. —Ameers or chieftains in their clans.

And the house of their fathers increased. —And their father-houses had spread greatly. Finding their territory too small for them under these conditions, and probably also because of the encroachments of their powerful neighbors, the Judeans and Philistines, the Simeonite chieftains set out at the head of their clans to seek new settlements.

And (so) they went to the entrance of Gedor, even to the east side of the valley. —Gedor can hardly be the town of that name in the hill country of Judah (Joshua 15:58). The Septuagint read Gerar (Γεραρα).

Even to the east side of the valley. —So far as to the east of the valley, that is, apparently, the valley of or near the unknown Gedor, or Gerar. The only considerable valley southeast of Judah is the Arabah, below the Dead Sea. That this locality is meant appears likely from the vicinity of Mount Seir and the Amalekites (1 Chronicles 4:42).

To seek pasture for their flocks. —This statement is of interest as proving that even as late as the reign of Hezekiah, those Israelite clans that bordered on the desert were still nomads, like the Beidawis. .