They also knew you will return but they lost track. (deviation in Mahdism issues)
“Kaysanites” believed in Muhamamd ibn Hanafyyah’s Imamate. Some people after his death, denied his death and said: “He is alive but he became absent and he has hidden in Razavi Mountain until he will be ordered and will reappear.” In fact, they know him as the awaiting Imam.
“Zeidieh” had heard the narration quoted by Prophet Muhammad: “Mahdi is a descendent of Imam Hussein and he would rise with his sword and his mother is one of the best maids.” Therefore, they believed that Zeid, the son of Imam Sajjad, as the promised Mahdi! He stood up against tyrants and the caliphs of Umayyad and he was martyred in 122 hegira.
“Bagherieh” believed that Imam Baqir will return and knew him as the awaiting Mahdi! Esmaeelieh knew Esamaeel the son of Imam Sadiq as the savior that will set justice in the world.
This was roughly, the story of Navusieh, Musavieh, Mohamadieh and Askarieh
Darsnameh Mahdaviat, volume 1, lesson 6