Genesis 25:16
These are the sons of Ishmael, and these are their names, by their towns, and by their castles; twelve princes according to their nations. These are the sons of Ishmael, and these are their names, by their towns, and by their castles; twelve princes according to their nations.
The listing belongs within the account of God's providential dealings with Abraham's family, whose line is connected with the promised Seed. It is part of the story of Abraham and his family, connected with Abraham's gradual development of faith and with Isaac and his two sons in their defects, leading to Jacob's victory that made him Israel, prevailer with God. It records the fulfillment of the prediction that Ishmael would have twelve sons who became princes, and the number twelve there merely describes what would happen and does not signify a special meaning attached to the twelve.
Each of Ishmael's twelve sons became the head of a tribe, as princes associated with their towns and nations. The descendants of the oldest son united with the Edomites in building up the Idumean kingdom with its marvelous rock-hewn capital Petra. Some Ishmaelites lived a settled life, but the great majority were nomads living in movable villages of tents throughout the desert region from the Euphrates westward. They carried on a large carrying trade across the desert and ravaged and plundered whenever opportunity presented itself. The Abyssinians are descendants of Abraham through Ishmael and therefore are Semitic.