The Shia after the death of Imam al-Hassan bin Ali al-Askari (died 260 hijri):
The shia of Imam al Hassan bin Ali split to more than ten groups:n A group said that Al Hassan bin Ali al Askari did not die but he is in occultation and he is al Qa’em (Mahdi), and it is haram to say he is dead. Because the earth will perish without an Imam, he also never had any children to succeed him. A group said that he died and then came back to life and he is al Qa’em al Mahdi. He is the Qa’em because he died and was resurrected and he has no children and if he did have a child then he wouldn’t have been resurrected because the Imamah would have been transmitted to his child. He didn’t give wasiyah to anyone thus he is surely the Qa’em .A group said Al Hassan bin Ali died and his successor is his brother Ja’afar whom he gave the wasiyah thus he is the Imam and his children after him. A group said that Ja’afar was the Imam but his brother Hassan wasn’t an Imam nor was his bother Muhammad. Because Muhammad died during the life of his father and al Hassan died without a son and he was a liar who claimed Imamah. The proof for them was that an Imam never passes away until he gives wasiyah to his successor thus al Hassan never had any children so his Imamah wasn’t correct. Also al Hassan & Ja’afar couldn’t be Imams at the same time because Abu Abdullah said “No two brothers shall become imams at the same time after Hassan & Hussein”. So Ja’afar took the wasiyah from his father not his brother. A group said the Imamah goes to Muhamad Bin Ali who died in the time of his father and that Hassan and Ja’afar claimed what isn’t rightfully theirs, and that their father never appointed or assigned any of them as Imams. And especially Ja’afar who has extremely negative qualities which make him unfit to receive it. As for Hassan he died without a son and that is unacceptable in an Imam. We now know that Muhammad is the Imam and his father pointed to him clearly.A group said that Al Hassan had a son who was born eight months after his death and all those who claimed he had a son during his life are liars because if he did then he wouldn’t hide this nor would his family. And companions hide it nor would that be acceptable of an imam. His father in his wasiyah ordered to call him Muhammad and the proof of this is a narration from Abu al Hassan al Redah. A group said there is no son for Hassan because we searched for this and asked for it but never found anything to point to his son. We cannot claim that he had a hidden son because then we could claim this for every dead Imam or we could even say that the prophet (sallalahu alaihi wa ala alihi wa sallam) had another son who was a prophet but is hidden. Also we could say Abdullah bin Ja’afar had a hidden son and that Abu al Hassan al Redah had three sons other thanAbu Ja’afar and one of them was the Imam. Because the news of al Hassan’s death without a son is like that of the prophet (sallalahu alaihi wa ala alihi wa sallam) dying without a son from his own blood. Or Abdullah bin Ja’afar having a son or Abu al Hassan having four sons. A group said the death of Al Hassan’s father and grandfather is true thus the news of his death. It is also true and there is no Imam after him and there is possibility that the Imamah will end at some point as we hear in the narration from the two Sadiqs that the earth will never be without an imam unless Allah is angry at the people because of their sins. So the Hujjah will be lifted for some time and Allah does what he wants and this does not mean that the concept of Imamah is incorrect in any way. This had also happened in the time between Muhammad (sallalahu alaihi wa ala alihi wa sallam) and Jesus (alaihi salam). In that period there was no Imam or prophet for 300 or 200 years, and al Sadiq said: The Period is the time when the earth will be without an Imam or a prophet. The earth today is without an Imam until Allah sends one from the progeny of Muhammad (sallalahu alaihi wa ala alihi wa sallam). A group said: Abu Ja’afar “Muhammad bin Ali” who died in his father’s life is the Imam by the order of his father who clearly mentioned his name. A group said when asked “Is Ja’afar or his brothers the Imams?”, they replied: We do not know if he is from Al Hassan’s brothers or from his progeny. Al Hassan was the Imam and he is now dead and the earth will never be without a hujjah. So we can’t say anything until this matter becomes clearer. A group said Al Hassan bin Ali was the Imam and he is dead so the Imamah goes to Ja’afar bin Ali, just like Musa bin Ja’afar was an Imam after Abdullah bin Ja’afar, because it was narrated that after an Imam passes away then the Imamah will be for the elder son. What Al Sadiq said “There will be no two brother Imams after Hassan and Hussein” this is true, but if the first one didn’t have a son then it must necessarily go to his brother As for the narration which states that “An Imam will be washed only by another Imam”, they said this is true and claimed that Ja’afar bin Muhammad was washed by Musa. They also claimed that Abdullah ordered this because he was the Imam after him but it’s ok that Musa did it because he is a silent Imam in the presence of Abdullah. This team is the Fathiyah who allow the Imamah of two brothers after Hassan and Hussein, if the first never had a son and according to this their Imam was Ja’afar bin Ali. A group said the Imam after al Hassan is his son Muhammad and he is al Hujjah but he is currently dead and when he is resurrected he will carry the sword and fill the world with justice and love after it was filled with hatred and oppression. A group said that all the others were wrong and that Al Hassan did have a son during his life called Muhammad and he is al Qa’em and he is alive and he has two Ghaybas (occultations) a minor one when his father dies and a major one after the death of Abu al Hassan ali bin Muhammad al Samiri the final emissary, and this has been going since that time.
Sources: look for details of each team in the book “Firaq al Shia” Page 96 by Al Hassan bin Musa Abu Muhammad al Nawbakhti, also in the books “Al Fusool al mukhtara” page 261 & “Bihar al Anwar” (37/20) and (50/336).