And he had thirty sons that rode on thirty ass colts, and they had thirty cities, which are called Havothjair unto this day, which are in the land of Gilead. (Judges 10:4)
This proves almost certainly that he was a polygamist, like Gideon.
Havoth-jair.
Literally, “tent villages of Jair.” This name was given to the region in the time of Moses when the earlier Jair captured a number of villages from Og, king of Bashan (Num. 32:41; Deut. 3:14). In the meantime more cities had sprung up or others had been captured, so that when Jair judged Israel he was able to give one to each of his 30 sons, who served as their prefects.
Gilead.
Literally, “hard,” or “rough.” It received the name from the characteristic rough mountain ridges. Gilead is divided in halves by the Jabbok River (Deut. 3:12; Joshua 12:2, 5). The southern half was conquered by Israel from the Amorite king Sihon (Joshua 12:2). The tribe of Gad settled on the southern half, and the northern half fell to Manasseh. Occasionally the term Gilead is used in the Bible with great elasticity, designating the entire land east of the Jordan as far north as Dan (Deut. 34:1).
Thirty ass colts.
In the days prior to the time of Solomon when the Israelites did not own horses, the possession of asses was a sign of wealth and therefore of honor and dignity. This fact is probably recorded to show the rich blessings of a man who had 30 sons, all of whom enjoyed the honor and distinction of riding as chiefs or governors.