the population of Classical Greece and 31 years for the population of thirteenth century England. The early Islamic Empire also had the highest literacy rates among pre-modern societies, alongside the city of classical Athens in the 4th century BC, and later, China after the introduction of printing from the 10th century. One factor for the relatively high literacy rates in the early Islamic Empire was its parent-driven educational marketplace, as the state did not systematically subsidise educational services until the introduction of state funding under Nizam al-Mulk in the 11th century. Another factor was the diffusion of paper from China, which led to an efflorescence of books and written culture in Islamic society; thus papermaking technology transformed Islamic society (and later, the rest of Afro-Eurasia) from an oral to scribal culture, comparable to the later shifts from scribal to typographic culture, and from typographic culture to the Internet. Other factors include the widespread use of paper books in Islamic society (more so than any other previously existing society), the study and memorisation of the Qur'an, flourishing commercial activity and the emergence of the Maktab and Madrasah educational institutions. Notable caliphs Rashidun ("Righteously Guided") Abu Bakr, first Rashidun caliph. Subdued rebel tribes in the Ridda wars. Umar (Umar ibn al-Khattab), second Rashidun caliph. During his reign, the Islamic empire expanded to include Egypt, Jerusalem and Persia. Uthman, (Uthman ibn Affan) third Rashidun caliph, When Caliph Umar died in office aged 59/60 years, Uthman, aged 64/65 years, succeeded him and was the second oldest to rule as caliph. Under Uthman's leadership, the Islamic empire expanded into Fars (present-day Iran) in 650, and some areas of Khorasan (present-day Afghanistan) in 651. The conquest of Armenia had begun by the 640s. Ali (Ali ibn Abu Talib), fourth Rashidun caliph. Considered by Shi'a Muslims however to be the first imam. His reign was fraught with internal conflict, with Muawiyah ibn Abi Sufyan (Muawiyah I) and Amr ibn al-As controlling the Levant and Egypt regions independently of Ali. Hasan ibn Ali, fifth caliph. Considered as "rightly guided" by several historians. He abdicated his right to the caliphate in favour of Muawiyah I in order to end the potential for ruinous civil war. "Umayyad Caliphate" Muawiyah I, the first caliph of the Umayyad dynasty. Muawiyah instituted dynastic rule by appointing his son Yazid I as his successor, a trend that would continue through subsequent caliphates. Abd al-Malik