An Islamic state (Arabic: الدولة الإسلامية ad-dawlah al-islamīyah) is a type of government, in which the primary basis for government is Islamic religious law (sharia). From the early years of Islam, numerous governments have been founded as "Islamic", beginning most notably with the caliphate established after the Islamic prophet Muhammad and including subsequent governments ruled under the direction of a caliph (meaning "successor" [to Muhammad]). However, the term "Islamic state" has taken on a more specific modern connotation since the 20th century. The concept of the modern Islamic state has been articulated and promoted by ideologues such as Abul A'la Maududi, Ayatollah Ruhollah Khomeini, Israr Ahmed, and Sayyid Qutb. Like the earlier notion of the caliphate, the modern Islamic state is rooted in Islamic law. It is modeled after the rule of Muhammad. However, unlike caliph-led governments which were imperial despotisms or monarchies (Arabic: malik), a modern Islamic state can incorporate modern political institutions such as elections, parliamentary rule, judicial review, and popular sovereignty.