Leah, Rachel, Bilhah, and Zilpah bore a total of twelve sons. Each of these twelve sons became the father of a tribe of Israel. Leah had Reuben, Simeon, Levi, Judah, Issachar, and Zebulun. Bilhah had Dan and Naphtali. Zilpah had Gad and Asher. Rachel had Joseph and Benjamin. Collectively, the sons are known as the twelve tribes of Israel because all Israelite people come from them.