Some time ago I heard a Dvar Torah (which I brought here) by someone who stated, among other things, that the city of Gilad used to be, at least from the time of the sale of Yosef until it was conquered by the Tribe of Menashe, a center for slave-trafficking. I don't remember if a source for this was brought. Does anyone know any source on the matter?
Well, as it turns out, the person who gave over the dvar Torah wrote down all of it here. It seems that it should be inferred that Gilad was a place of slave-trafficking because the Yishmaelim came from there and they were obviously slavers, because both the brothers thought to sell Yosef to them upon seeing them and the Yishmaelim themselves immediately agreed to the sale when it was offered to them.