The term caliphate simply means an Islamic state and community, and the caliph is the community leader (per Britannica). It has a long history within Islam, dating back to the time of the first successors of Muhammad. During this period, Muslims organized themselves together as both a religion and a state, which became known as a caliphate.
After Muhammad died, the rule by his first four successors become known as the Rashidun Caliphate, which means rightly guided caliphate in Arabic, per "A History of the Modern Middle East." Following the Rashidun Caliphate was the Umayyad and Abbasid Caliphates, which lasted from 661 A.D. to 750 A.D., and 750 A.D. to 1248 A.D., respectively. It was during these caliphates that the Muslim community expanded incredibly rapidly, conquering large swathes of territory in Asia, North Africa, and Spain.
The last widely recognized caliphate was the Ottoman Empire, which ceased in 1924 as the empire disintegrated. According to an article in the Economist in 1924, by then the caliphate was seen as outdated and incompatible with the ideals of democracy and nationalism. Instead of a supreme Islamic leader, modern Turkey was to be led by an elected parliament, and focused on nationalist rather than religious goals.
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