Arabs show up in three biblical lists of genealogy:
The descendants of Jaktan (Genesis 10:25-30)
The descendants of Abraham through Keturah (Genesis 10:1-6)
The descendants of Ishmael (Genesis 25:13-18)
(It is possible that some of the descendants of Cush, the son of Ham (Genesis 10:7) are also called Arabs.)
There seems to have been some intermingling between the tribe of Simeon and the Ishmaelites, for the clans of Mibsam and Mishma are associated with both. (Genesis 25:13 and I Chronicles 4:25).
Ishmaelites do not appear among the victims of David's raids into the lands south and east of Israel, even though these enter Arab lands. (I Samuel 27:8 and Genesis 25:18) David's sister married Jether the Ishmaelite (I Chronicles 2:17) and two of David's administrators were Obil the Ishmaelite, and Jaziz the Hagarite, (I Chronicles 27:30).
Hagar and Ishmael were given Arabia (Genesis 21:8-21) and Isaac's descendants were promised the Holy Land. Apparently they were not hostile to each other, for Ishmael and Isaac worked together to bury their father Abraham in the Cave of Macphilah, in Mamre (Genesis 25:9).
On the other hand, the Bible refers to various individuals and groups as being 'Arabs.' Jeremiah prophesied against the 'kings of the Arabs' sometime between 627 and 586 BC.
The Arab genealogist Hisham Ibn Muhammad al-Kalbi (A.D. 737-819), known as Ibn al Kalbi, established a genealogical link between Ishmael and Mohammed. He quotes writers who had access to biblical and Palmyran sources, but the majority of his information came from the ancient oral traditions of the Arabs. His book, 'Djamharat al Nasab' has been translated into German by W. Caskel, (Ghamharat an-Nasab (The Abundance of Kinship) Das genealogische Werk des Hisam Ibn Muhammad al Kalbi, Leiden: E. J. Brill, 1966) It seemed to be Ibn al Kalbi's opinion that the people known as 'Arabs' were all descendants of Ishmael.
It is the common view of Arab genealogists and modern historians that Arabs originated in the southern part of the Arabian Peninsula, and then moved northward. (James Montgomery, Arabia and the Bible, Philadelphia, University of Pennsylvania Press, 1934 and Hitti, History of the Arabs.) This view is based on the identification by Muslim Arabs of their oldest ancestor as being Qahtan, whom they identify as the biblical Jaktan. Genesis 10:25-26.
Arab Genealogists divide the Arabians into two ethnic stocks. First, the original Arabic Arabs ('aribah) and then the arabized Arabs (musta 'iribah). The Arabic Arabs are supposed to have originated with the Yamanites and are descended from Qahtan (Jaktan of the Bible) and are the original stock. The Arabized Arabs are the Hijazis, Najdis, Nabataeans, and Palmyrenes. These Arabized Arabs are supposed to have all descended from Adnan, an offspring of Ishmael.
Records of Other Civilizations
This Greco-Roman term appears in classical literature, and stems most likely from the Arabic Sarqiyyun, meaning 'easterners.' Fergus Millar in 'Hagar, Ishmael, Josephus, and the Origin of Islam, JJS 44(1983): 41-43 claims that this term refers mostly to Ishmaelites. Musil in Arabia Deserta, (494) refers to the nomadic tribes living in the inner desert of central Arabia as bedw or sarkiyye, a term derived from sarq, which means 'east' in Arabic, but is often used as a reference to the inner desert of north and central Arabia. "Whoever marches through this region, whether he goes west or east or south, is referred to as sarrak tasriz or going into the inner desert."