According to the History of Judaism, the Bible states that God chose Abraham to be the father of His chosen people. Eventually, these people became known as Jews.
In Genesis 17:6-7, God says to Abraham: "And I will make thee exceeding fruitful, and I will make nations of thee, and kings shall come out of thee. And I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant, to be a God unto thee, and to thy seed after thee." At the time, Abraham did not believe God because he and his wife, Sarah, were too old to have a child of their own. Eventually, Abraham and Sarah had a son, Isaac, who became the father of Jacob who was also called "Israel" by God. Jacob's sons became the 12 tribes of Israel.