Bayān b. Samʿān (or Simʿān) al-Tamīmī al-Nahdī (d. 119/737), was a Kaysānī Shiʿi and a ghālī (extremist Shiʿi), from whom the Bayāniyya take their name. His father’s name Samʿān, or Simʿān (Simeon), suggests that he may have come from an Aramaean family background. His nisba is sometimes given as al-Tamīmī, but it is more likely that he belonged to the South Arabian Banū Nahd, who played an important role in al-Mukhtār’s rebellion in Kūfa in 66–67/685–687. Bayān’s name is sometimes erroneously recorded as Banān (see al-Kashshī, 301, 304; …