Iraq and Kufa in particular became centres of pro-Alid support.[1][2] It was the Abbasids, however, and their supporters, the Hashimiyya, who launched the revolution that overthrew the Umayyad regime. The Abbasids claimed authority based on their membership in the extended Al Muhammad through Muhammad's uncle Abbas ibn Abd al-Muttalib; unlike later Shi'a doctrine, membership of the Family was not strictly limited to the Alids at that time, but encompassed the entire Banu Hashim. The Abbasids were able to exploit the weakening of the Alid cause after Zayd's failure in 740, as well as the widespread anti-Umayyad sentiment and lack of pro-Alid agitation among the numerous Arab settlers of Khurasan, to gain their backing and secure the leadership of the anti-Umayyad movement for themselves.