The Abbasid Caliphate was the third Islamiccaliphate. It was established by the descendants of Muhammad's uncle, Abbas ibn Abd al-Muttalib. It was founded in 750, and shifted its capital in 762 to Baghdad. It flourished for two centuries, although Abbasid rule was ended in 1258, when the Mongolssacked Baghdad. But they continued to claim authority in religious matters from their new base in Egypt.
During the period of the Abbasid dynasty, Abbasid claims to the caliphate did not go unchallenged. The Shiˤa Fatimid dynasty, which claimed descent from Muhammad through his daughter, claimed the Caliphate in 909 and created a separate line of caliphs in North Africa until 1171. The Umayyad dynasty, which had survived to rule over Spain, reclaimed the Caliphate in 929, lasting until it was overthrown in 1031.
↑The Abbasid Revolution against the Umayyad Caliphate adopted black for its rāyaʾ for which their partisans were called the musawwids. Tabari (1995), Jane McAuliffe (ed.), Abbāsid Authority Affirmed, vol.28, SUNY, p.124
Their rivals chose other colours in reaction; among these, forces loyal to Marwan II adopted red. Patricia Crone (2012). The Nativist Prophets of Early Islam. p.122. ISBN9781107018792.. The choice of black as the colour of the Abbasid Revolution was already motivated by the "black standards out of Khorasan" tradition associated with the Mahdi. The contrast of white vs. black as the Umayyad vs. Abbasid dynastic colour over time developed in white as the colour of Shia Islam and black as the colour of Sunni Islam: "The proselytes of the ʿAbbasid revolution took full advantage of the eschatological expectations raised by black banners in their campaign to undermine the Umayyad dynasty from within. Even after the ʿAbbasids had triumphed over the Umayyads in 750, they continued to deploy black as their dynastic colour; not only the banners but the headdresses and garments of the ʿAbbasid caliphs were black ... The ubiquitous black created a striking contrast with the banners and dynastic color of the Umayyads, which had been white ... The Ismaili Shiʿite counter-caliphate founded by the Fatimids took white as its dynastic color, creating a visual contrast to the ʿAbbasid enemy ... white became the Shiʿite color, in deliberate opposition to the black of the ʿAbbasid 'establishment'." Jane Hathaway, A Tale of Two Factions: Myth, Memory, and Identity in Ottoman Egypt and Yemen, 2012, p. 97f. After the revolution, Islamic apocalyptic circles admitted that the Abbasid banners would be black but asserted that the Mahdi's standard would be black and larger. David Cook (2002). Studies in Muslim Apocalyptic, p. 153.
Anti-Abbasid circles cursed "the black banners from the East", "first and last". Patricia Crone (2012). The Nativist Prophets of Early Islam. p.243. ISBN9781107018792.
↑Abbasid (Arabic: لعبّاسيّون, transcription al-‘Abbāsīyūn) is the dynastic name generally given to the caliph of Baghdad
↑History of al-Tabari Vol. 34, The: Incipient Decline, page 149