Arab tribes, most notably the Ghassanids and Lakhmids, begin to appear in the southern Syrian Desert from the mid 3rd century CE onward, during the mid to later stages of the Roman and Sasanian empires.Before the expansion of the Rashidun Caliphate (632–661), "Arab" referred to any of the largely nomadic and settled Semitic people from the Arabian Peninsula, Syrian Desert, North and Lower Mesopotamia.
Arab Muslims primarily belong to the Sunni, Shiite, Ibadi, Alawite, Druze and Ismaili denominations.
Arab Christians generally follow one of the Eastern Christian Churches, such as the Maronite, Coptic Orthodox, Greek Orthodox, Greek Catholic or Chaldean churches. The earliest documented use of the word "Arab" to refer to a people appears in the Kurkh Monoliths, an Akkadian language record of the ninth century BCE Assyrian conquest of Aram, which referred to Bedouins of the Arabian Peninsula under King Gindibu, who fought as part of a coalition opposed to Assyria.
This makes them the world's second largest ethnic group after the Han Chinese.
Arabs are a diverse group in terms of religious affiliations and practices.
The most popular Arab account holds that the word "Arab" came from an eponymous father called Ya'rub who was supposedly the first to speak Arabic.
Abu Muhammad al-Hasan al-Hamdani had another view; he states that Arabs were called Gharab ("West") by Mesopotamians because Bedouins originally resided to the west of Mesopotamia; the term was then corrupted into "Arab".And Ishmael and his sons, and the sons of Keturah and their sons, went together and dwelt from Paran to the entering in of Babylon in all the land towards the East facing the desert.And these mingled with each other, and their name was called Arabs, and Ishmaelites.The root ʿ-r-b has several additional meanings in Semitic languages—including "west/sunset," "desert," "mingle," "mixed," "merchant," and "raven"—and are "comprehensible" with all of these having varying degrees of relevance to the emergence of the name.It is also possible that some forms were metathetical from ʿ-B-R "moving around" (Arabic ʿ-B-R "traverse"), and hence, it is alleged, "nomadic." Pre-Islamic Arabia refers to the Arabian Peninsula prior to the rise of Islam in the 630s.Arab tribes came into conflict with the Assyrians during the reign of the Assyrian king Ashurbanipal, and he records military victories against the powerful Qedar tribe among others.