History -- 45 Caliphs 14 Islamic Empire -- 13 History 7 Biography 4 Caliphate 4 Caliphs -- 4 more ... Islam 4 Islam -- 2 Leadership -- 2 Politics and government 2 Religious aspects -- 2 Riddah Wars 2 Siffin, Battle of, Syria, 657 2 Abbasids 1 Apostasy -- 1 Caliphate -- 1 Camel, Battle of the, Iraq, 656 1 Circassians -- 1 Economic consitions 1 Historiography -- 1 Industries -- 1 Islam and politics -- 1 Islamic Empire 1 Islamic civilization 1 Muslims -- 1 Occupations -- 1 Opposition (Political science) -- 1 Political parties -- 1 Relations -- 1 less ...