Caliphate of Umar IIMedina Saudi Arabia
Umar ibn Abd al-Aziz was the eighth Umayyad caliph. He made various significant contributions and reforms to the society, and he has been described as "the most pious and devout" of the Umayyad rulers and was often called the first Mujaddid and sixth righteous caliph of Islam.He was also a cousin of the former caliph, being the son of Abd al-Malik's younger brother, Abd al-Aziz. He was also a matrilineal great-grandson of the second caliph, Umar ibn Al-Khattab.
Surrounded with great scholars, he is credited with having ordered the first official collection of Hadiths and encouraged education to everyone. He also sent out emissaries to China and Tibet, inviting their rulers to accept Islam. At the same time, he remained tolerant with non-Muslim citizens. According to Nazeer Ahmed, it was during the time of Umar ibn Abd al-Aziz that the Islamic faith took roots and was accepted by huge segments of the population of Persia and Egypt. Militarily, Umar is sometimes deemed a pacifist, since he ordered the withdrawal of the Muslim army in places such as Constantinople, Central Asia and Septimania despite being a good military leader. However, under his rule the Umayyads conquered many territories from the Christian kingdoms in Spain.