Son of Imam Musa (seventh imam) The Eighth ImamImam Ridha/Reza (Ali ibn Musa) was the son of the seventh Imam and according to well known accounts was born in 148/765 and died in 203/817.The eighth Imam reached the Imamate, after the death of his father, through Divine Command and the decree of his forefathers. The period of his Imamate coincided with the caliphate of Harun and then his sons Amin and Ma'mun. After the death of his father, Ma'mun fell into conflict with his brother Amin which led to bloody wars and finally the assassination of Amin, after which Ma'mun became caliph. Until that day the policy of the Abbasid caliphate toward the Shia had been increasingly harsh and cruel.
Son of Imam Ja'far (sixth imam) The Seventh ImamImam Musa ibn Ja'far Kazim, the son of the sixth Imam, was born in 128/744 and was poisoned and martyred in prison in 183/799. He became Imam after the death of his father, through Divine Command and the decree of his forefathers.The seventh Imam was a contemporary of the Abbasid caliphs, Mansur, Hadi, Mahdi and Harun. He lived in very difficult times and in hiding, until finally Harun went on the Hajj. In Medina, he had the Imam arrested while praying in the Mosque of the Prophet (sawas). He was chained and imprisoned, then taken from Medina to Basra and from Basra to Baghdad where for years he was transferred from one prison to another. Finally he died in Baghdad in the Sindi ibn Shahak prison through poisoning and was buried in the cemetery of the Quraysh which is now located in the city of Kazimayn.
Son of Imam Muhammad (Fifth Imam) The Sixth ImamImam Ja'far ibn Muhammad Al-Sadiq, the son of the fifth Imam, was born in 83/702. He died in 148/785 according to Shia tradition, poisoned and martyred through the intrigue of the Abbasid caliph Mansur. After the death of his father he became Imam by Divine Command and decree of those who came before him.
Son of Imam Ali (Fourth Imam) The Fifth ImamImam Muhammad ibn Ali Baqir (the word Baqir meaning he who cuts and dissects, a title given to him by the Prophet (sawas)) was the son of the fourth Imam and was born in 67/675. He was present at the event of Kerbala when he was four years old. After his father, through Divine Command and the decree of those who went before him, he became Imam.
Son of Imam Hussein (Third Imam) The Fourth ImamImam Sajjad (Ali ibn Husayn entitled Zayn al-'abedin and Sajjad) was the son of the third Imam and his wife, the queen among women, the daughter of Yazdigird the king of Persia. He was the only son of Imam Husayn to survive, for his other three brothers Ali Akbar, aged twenty-five, five year old Ja'far and Ali Asghar (or 'Abdallah) who was a suckling baby were martyred during the event of Kerbala.
Son of Imam Ali (First Imam) The Third ImamImam Husayn (Sayyid al-Shuhada', "the lord among martyrs"), the second child of Ali and Fatimah, was born in the year 4 A.H. and after the martyrdom of his brother, Imam Hasan Mujtaba, became Imam through Divine Command and his brother's will.