library and translation institute established in Baghdad by al-Ma'mun, Abbasid caliph, to transfer the knowledge of Greeks, Persians, Indians, etc. to the Muslim world. The Compendious Book on Calculation by Completion and Balancing, a book of algebra, is also written there by Al-Khwarizmi. 835: Sweet Dew Incident occurs. Emperor Wenzong of the Tang Dynasty conspires to kill the powerful eunuchs of the Tang court, but the plot is foiled. 839–842: Vlastimir defeats Presian. 840: Death of Louis the Pious. 841: Dublin is founded on the east coast of Ireland by the Vikings. 842: Samaale becomes chief of the Hashiyah clan and launches the conquest of Somalia. This paves the way for Hashiyic colonisation of the Peninsular, displacing the native Cushitic peoples of Somalia 843: The Carolingian Empire is at its height in territory and area. The three sons of Louis the Pious reach an agreement known as the Treaty of Verdun and split the Carolingian empire into three divisions; East Francia was given to Louis the German, West Francia to Charles the Bald and Middle Francia to Lothair I. 844: The first Viking raid in Iberia 845: Buddhism is persecuted and banned in China. 846–859: Emperor Xuānzong of Tang reigned. He was considered the last capable emperor of the Tang dynasty. 846: 11,000 Saracen Arab squadrons from Africa, with 500 horses, desecrate Christian shrines in Rome, including the tombs and basilicas of Sts. Peter and Paul. 848–852: The west bank of the Tiber is annexed into the city of Rome. A defensive wall, commissioned by Pope Leo IV, is built around what came to be called the Leonine City as a defensive response to the Saracen desecration of Rome in 846. 850–875: The first Norse settlers arrive on Iceland. 851: The Arab merchant Sulaiman al-Tajir visits the Chinese seaport at Guangzhou in southern China, and observes the manufacturing of porcelain, the Islamic mosque built at Guangzhou, the granary system of the city, and how its municipal administration functioned. 856: Prambanan is completed. According to the Shivagrha inscription, Rakai Pikatan — the husband of Pramodhawardhani — defeated Balaputra. 859: Muslims establish the University of Al Karaouine as a madrasa in Fez, Morocco. 860: Balaputra, the maharaja of Suvarnadvipa and the ruler of Srivijaya, constructs the Buddhist temple and monastery in Nalanda India, on the land given by King Devapaladeva. of Pala in Benggala, according to the Nalanda inscription. 861: Assassination of