The Arab people count their ancestry through Ishmael, the son of Abraham and Hagar. Ishmael had twelve sons. Here are the passages:
Genesis 17:20 And as for Ishmael, I have heard thee: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation.
Genesis 25:12-16 Now these are the generations of Ishmael, Abraham's son, whom Hagar the Egyptian, Sarah's handmaid, bare unto Abraham: And these are the names of the sons of Ishmael, by their names, according to their generations: the firstborn of Ishmael, Nebajoth; and Kedar, and Adbeel, and Mibsam, And Mishma, and Dumah, and Massa, Hadar, and Tema, Jetur, Naphish, and Kedemah: These are the sons of Ishmael, and these are their names, by their towns, and by their castles; twelve princes according to their nations.
Now, it is possible that these twelve sons (being twelve princes) ruled over twelve tribes of Ishmael. However, I know of no scripture that speaks of the descendants of these sons of Ismael as tribes of the Arab people. Perhaps this information can at least get you started in your study.
