One of Noah's descendants was named Abram.  God told Abram to leave his father's household and country and go to a new land.  So Abram left, and took his wife Sarai and nephew Lot with him.  After reaching the land God promised, there was a famine, so they went down to Egypt where there was food.  After the famine, they left Egypt and returned to the land.  By this time, both Abram and Lot had acquired great flocks and herds and tents.  They parted company so that the land could support their livestock and families.