Genesis 10:24-25

Arphaxad begat Salah— Who established himself, as there is great reason to believe, in Susiana: he begat Eber, who begat two sons, the name of one of whom was Peleg, (division,) so called, because the earth was, by mutual compact, divided among these descendants of Noah in his days. This division was made, it is supposed, at the time of Peleg's birth, more than one hundred years after the flood, when there must have been great numbers upon the earth. Though others are of opinion, that there is no need to confine it to the time of Peleg's birth, as they think the name might be given him in a prophetic view, as Noah's and many others were; and consequently, any period of Peleg's life (suppose when he was a hundred years old, as he lived to be two hundred and thirty nine) may be assigned for that event; in which case there might have been some millions upon the earth at that time; that is, suppose the division to have been made two hundred years after the flood. And there is no reason to suppose, that all the persons here mentioned went to the several countries they possessed at one and the same time: the different plantations, most probably, were made at different times, and by a gradual progression.