By some means unknown to us, the ancient world was surveyed and apportioned to the descendants of Noah. It is possible that this was the division of the lands mentioned in Genesis 10:25, Genesis 10:32, and Deuteronomy 32:8.

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8