The Kaysāniyya sect

The Kaysanite sect is classified in the Ghulat group. After the martyrdom of Imam Hussayn (may peace be upon him), a group of people followed the Imamah of Muhammad Ibn al-Hanafiyyah.

For the Shias, the fourth Imam from the progeny of Fatima is Imam Ali ibn Hussayn Zayn al-Abidin (may peace be upon him)

From wikipedia

One Kaysanite sub-sect was led by the Abbasids, who successfully revolted against the Umayyad Caliphate and then established the Abbasid Caliphate. However, following the establishment of the Abbasids as Caliphs and their disavowal of their Kaysanite origins, the majority of the Kaysanites responded by abandoning the Kaysanite Shi'a sect and instead switched their allegiances to other Shi'a sects. Thereafter, the Kaysanite Shi'a sect became extinct despite its once dominant position among the Shi'a.

Some of the Kaysanite sects believe that after the death of Muhammad ibn al-Hanafiyyah, he was the promised Mahdi who is in concealment. One of the Ghulat beliefs of the Kaysaniyya sect is believing in the transmigration of souls (tanaukh al-arwah i.e. the return in a different body while having the same spirit).