As we have said above, Khilafat or Caliphate was the political organisation of the Muslim community under the four Orthodox Caliphs. When the Umayyad dynasty (661-710) came to power in 661 A.D./32 A.H., it kept its outward form but changed it into a monarchy. The Caliphal structure remained the same under the Abbasids (750-1258), but with one important change: they upheld the authority of the Shariah. Under the Abbasids, the Caliph remained the political and religious leader of the Muslim Ummah.
But when the Abbasid Caliphate began to decline from about 940 A.D, the Caliphal authority was challenged by rival Caliphs in both the eastern and western provinces of the Caliphate, while independent Muslim rulers or sultans usurped the political authority of the Abbasid Caliphs.
This critical situation made several Muslim political thinkers to expound various theories of the Caliphate. Among them al-Mawardi, al- (ihazali and Ibn Khaldun were most important.