Iranian Shiite mourners during Ashura, the 10th day of Muharram, on July 6, 2025, in Tehran. Majid Saeedi/Getty Images August 18, 2025 Twelver Shiism – a branch of Islam that serves both as a spiritual and political force in Iran and beyond Massumeh Toosi, Indiana University Twelver Shiites believe in a continuous line of 12 imams, all regarded as descendants of the Prophet Muhammad.
