Arwa al-Sulayhi
Arwa al-Sulayhi was the Hujjah from the time of Imam Mustansir. She appointed Dai in Yemen to run religious affair. Ismaili missionaries Ahmed and Abdullah (in about 1067 AD (460 AH)) were sent to India in that time. According to Fatimid tradition, after the death of Al-Amir bi-Ahkami'l-Lah, Arwa al-Sulayhi instituted the Da'i al-Mutlaq in place of Dai to run the independent dawah from Yemen in the name of Imam Taiyab. The Dais are appointed one after other in the same philosophy of "nass" (nomination by predecessor) as done by earlier imams. It is believed that God's representative cannot die before appointing his true successor. This is being followed from the time of 3rd Imam Ali ibn Husayn Zayn al-Abidin, the strong army of Yazid also could not think of killing him, although they did not spare even a child of six months, Ali al-Asghar ibn Husayn.