The dar al-Islam, in theory, was in a state of war with the dar al-harb, because the ultimate objective of Islam was the whole world. If the dar al-harb were reduced by Islam, the public order of Pax Islamica would supersede all others, and non-Muslim communities would either become part of the Islamic community or submit to its sovereignty as tolerated religious communities or as autonomous entities possessing treaty relations with it. The strategy to bring about this universal system would be named jihad, an obligation binding on believers to expand their faith through struggle.
