Arabian tribes in the context of "Demographics of the Arab world"

The word "Saracen" (/ˈsærəsən/ SARR-ə-sən) was commonly used in medieval Europe to refer to a person who lived in or near what the ancient Romans knew as Arabia Petraea and Arabia Deserta. Its original meaning in Greek and Latin is not known with certainty. By the early medieval period, it had come to be associated with the Arabian tribes. Following the rise of Islam, which occurred in Arabia, the word's definition evolved to refer not only to Arabs, but to Muslims as well. It eventually became the standard adjective among European Christians for all people and things from the Muslim world, regardless of whether they were Arab in origin.

The oldest known source mentioning "Saracens" in association with Muslims is the Greek-language Christian tract Doctrina Jacobi, which was compiled in the Byzantine Empire amidst the Muslim conquest of the Levant. The word became particularly widespread in European societies during the Crusades, when it was used by the Roman Catholic Church and by several European Christian political and military figures.

The Banū Aws (Arabic: بنو أوس  pronounced [ˈbanuː ʔaws], "Sons of Aws") or simply Aws (Arabic: أوس, also romanised as Aus) was one of the main Arab tribes of Medina. The other was Khazraj, and the two, constituted the Ansar ("Helpers of Muhammad”) after the Hijra.

The Aws tribe descend from the ancient tribe al-Azd, a branch of the Qahtanite Arabs Aws and Khazraj were known as Banū Qayla (بنو قيلة  [ˈbænuː ˈqɑjlæ]) in pre-Islamic era.

The Ansar (Arabic: الأنصار, romanized: al-Anṣār, lit. 'The Helpers' or 'Those who bring victory'), also spelled Ansaar or Ansari, were the local inhabitants of Medina (mostly Muslims) who supported the Islamic prophet Muhammad, and his followers (the Muhajirun), when they fled from Mecca to Medina during the hijrah. The Ansar belonged to the Arabian tribes of Banu Khazraj and Banu Aws.