1) The Arabs have two broad categories - the extinct Ancient Arabs and the remaining Arabs who are divided into pure Arabs and Arabs who became Arabized. 2) The Prophet (sws) was an Adnani Arab, descended from Adnan who lived around 30 BC. 3) The Prophet's lineage is divided into three categories - the 20 generations between Adnan and him, the unknown number between Adnan and Ishmael, and the lineage from Ishmael to Adam which comes only from the Old Testament which can't be fully relied on.