was the fifth Umayyad caliph, ruling from April 685 until his death in 705. A member of the first generation of born Muslims, his early life in Medina was occupied with pious pursuits. He held administrative and military posts under Caliph Mu'awiya I (r. 661–680) and his own father, Caliph Marwan I (r. 684–685). Al-Walid I was the sixth Umayyad caliph, ruling from October 705 until his death. He was the eldest son of his predecessor Caliph Abd al-Malik. Umar ibn Abd al-Aziz (Umar II), Umayyad caliph who is considered one of the finest rulers in Muslim history. He is also considered by some (mainly Sunnis) to be among the "rightly guided" caliphs. Yazid II was the ninth Umayyad caliph, ruling from February 720 until his death in 724. Hisham was the tenth Umayyad caliph who ruled from 724 until his death in 743. Hisham was a great patron of the arts, and he again encouraged arts in the empire. He also encouraged the growth of education by building more schools, and perhaps most importantly, by overseeing the translation of numerous literary and scientific masterpieces into Arabic. He returned to a stricter interpretation of the Sharia as Umar had, and enforced it, even upon his own family. Al-Walid II was an Umayyad caliph who ruled from 743 until his death in the year 744. Yazid III was the twelfth Umayyad caliph. He reigned for six months, from 15 April to 3 or 4 October 744, and died in that office. Marwan II was the fourteenth and last Umayyad caliph, ruling from 744 until his death in 750. "Abbasid Caliphate" As-Saffah was the first caliph of the Abbasid caliphate, one of the longest and most important caliphates (Islamic dynasties) in Islamic history. Al-Mansur was the second Abbasid caliph reigning from 136 AH to 158 AH (754–775) and succeeding his brother al-Saffah. Al-Mansur is generally regarded as the greatest caliph of the Abbasid dynasty. He is also known for founding the 'round city' of Madinat al-Salam which was to become the core of imperial Baghdad Al-Mahdi was the third Abbasid caliph who reigned from 775 to his death in 785. Harun al-Rashid, Abbasid caliph during whose reign Baghdad became the world's prominent centre of trade, learning and culture. Harun is the subject of many stories in the famous One Thousand and One Nights. Al-Ma'mun, a great Abbasid patron of Islamic philosophy and