Matthew Poole and continuators on Genesis 36:15

15 These were Dukes of the sons of Esau; the sons of Eliphaz, the first-born son of Esau, Duke Teman, Duke Omar, Duke Zepho, Duke Kenaz,

Princes or Heads of their several Families and little Principalities, according to the manner of those times, who ruled their Dominions, either severally, each his own, or jointly by common advice, or, it may be, under one chief Prince, their superiour either in Title or in power. And in this division Eliphaz, as he was Esaus first-born so he had more than a double portion, his six sons being made Dukes, as Esaus immediate Sons were. Compare 1 Chron. 5. 1.