Final answer:
The rise of the Fatimid Caliphate was influenced by religious schisms within the Islamic community and the political fragmentation of the Abbasid Caliphate, leading to the establishment and expansion of the Fatimids, who later faced internal and external challenges, including military conflicts and succession issues.
Step-by-step explanation:
The circumstances that led to the rise of the Fatimid Caliphate are closely linked to religious schisms within Islamic communities, the political devolution of the Abbasid Caliphate, and the appearance of rivals who seized Abbasid territory. The Fatimid dynasty, which was part of the Shi'a faction of Islam, emerged in the 10th century and quickly grew to challenge the rule of the Sunni-dominated Abbasids. Claiming descent from Fatima, the daughter of Prophet Muhammad, the Fatimids at their peak controlled vast territories from present-day Algeria to Syria, and they established Cairo as their capital in 969.
However, the Fatimid Caliphate faced internal instability and external challenges, including conflicts with the Seljuk Turks and fragmented power due to the incorporation of Turkic cavalry, which alienated traditional Amazigh supporters. Further weakening came from the military strength of the Christian Crusaders, who captured Jerusalem in 1099. Eventually, a power struggle within the Fatimid realm led to a plea for support from competing factions, including the Crusaders and a Sunni Muslim army, which resulted in the intervention of Saladin and the eventual return of Egypt to Sunni Abbasid control.
The broader context of the Fatimid rise in power included dissatisfaction with Abbasid rule, the appearance of competing claims to caliphal authority, and the failure of institutions within the Islamic kingdoms to ensure stable succession, which often resulted in whoever had the military strength imposing law and order.