Albert Barnes Commentary Deuteronomy 4:41-43

"Then Moses set apart three cities beyond the Jordan toward the sunrising; that the manslayer might flee thither, that slayeth his neighbor unawares, and hated him not in time past; and that fleeing unto one of these cities he might live: [namely], Bezer in the wilderness, in the plain country, for the Reubenites; and Ramoth in Gilead, for the Gadites; and Golan in Bashan, for the Manassites." — Deuteronomy 4:41-43 (ASV)

These verses are inserted between two distinct and complete discourses for the reason to which they themselves call attention (Then Moses severed three cities, etc.); that is, the fact narrated took place historically after Moses spoke the one discourse and before he delivered the other. In thus severing the three cities of refuge, Moses carried out a previous command of God (see the marginal references); and so followed up his exhortations to obedience by setting a punctual example of it, as far as opportunity was given him.

In the plain country - literally, “in the land of the Mishor.” The word means a level tract of land; but when used (Deuteronomy 3:10; Joshua 13:9, and other passages) with the article, seems to be the proper name for the smooth downs of Moab, which reach from the Jordan eastward of Jericho far into the Desert of Arabia, and which form a striking contrast alike to the rugged country west of the river, and to the higher and remarkable districts belonging to Bashan northward.

Bezer is, with little certainty, identified with Bostra, or Bosor. Golan gave the name of Gaulonitis to a district of some extent east of the Sea of Galilee and north of the Hieromax; but the exact site of the city is uncertain.