sentences:  According to Fatimid tradition, in the year 985, the 15th Fatimid Caliph, Abu Mansoor Nizar al-Aziz Billah, traced the site of his great-grandfather's head through the office of a contemporary in Baghdad.It remained buried in the town of Ashkelon for about 250 years, until 1153.After the 21st Fatimid Imam At-Tayyib Abu'l-Qasim went into seclusion, his uncle, Abd al Majid, occupied the Fatimid Empire's throne.