Medieval Muslim chroniclers report that in 1050 or 1051, the Sulaymi and Hilali nomads were dispatched or encouraged to migrate to and take over Ifriqiyah by the Fatimids to punish that region's Zirid rulers for switching allegiance to the rival Abbasid Caliphate. However, Baadj urges that such reports "ought to treat[ed with skepticism" as the Fatimid state at the time was undergoing the Great Crisis, which was marked by a long famine and severe political instability. Thus, the Fatimids were not in a position to coerce the two Bedouin tribes to invade the Zirid realm; rather, the poor conditions in Egypt, namely the threat of starvation, motivated the Banu Sulaym and Banu Hilal to migrate westward into the Maghreb. The migration may have taken place in one large wave or in multiple waves, but in any case, the Sulaym apparently established themselves in Cyrenaica and Tripolitania, while the Banu Hilal continued on to Zirid-held Ifriqiyah and Qayrawan.