Jafar ibn Muhammad
After the death of Jafar ibn Muhammad, division occurred among Shias on the question of next Imam. Some said that his eldest son, Ismail ibn Jaffar (who had died before his father) to be the next imam, while the majority of Shiites said that his third son Musa al Qazim should be the  next imam. The first group became known as the Ismailis and the second, larger group was named Jafari or the Twelvers.