the Saxons for more than thirty years and finally crushing their rebellion, incorporating Saxony into the Frankish Empire and the Christian world. 775: Death of caliph al-Mansur and he was succeeded by al-Mahdi. 778: Kalasan temple constructed, according to the Kalasan inscription. 781: Marriage of Abbasid princess Zubaidah and Harun al-Rashid. The Xi'an Stele is erected in China. 782: Buddhist monk Prajna reaches Chang'an and translates the sutras into Chinese. 785: Death of Abbasid caliph al-Mahdi and succession of al-Hadi on 24 July 785. The Tang dynasty begins landing regular maritime missions on the coast of East Africa, cutting out middlemen Arab sea merchants. 785–805: Chinese geographer Jia Dan describes large lighthouse pillars built in the Persian Gulf, which is confirmed a century later by al-Mas'udi and al-Muqaddasi. 787: The Empress Irene of Athens convenes the Seventh Ecumenical Council, ending the first phase of Byzantine Iconoclasm. 786: Death of Abbasid caliph al-Hadi and ascension of caliph Harun al-Rashid. 792: Battle of Marcelae. The Bulgarian victory over the Byzantines marks the end of the half-century political instability in Bulgaria. 792: The Manjusrigrha (Sewu) temple is completed according to Manjusrigrha inscription. 793: The first written account of a Viking raid carried out on the abbey of Lindisfarne in northern England. 793: The Frisian–Frankish wars come to an end with the last uprising of the Frisians. 794: Emperor Kanmu moves the capital to Heian-kyō (present day Kyoto), initiating the Heian period of Japan. 800: An Arab fleet sails up the Tiber. 800–909: Rule of Aghlabids as an autonomous province of Caliphate in North Africa, with their capital at Tunis. 800: Beginning of the ancient West African state of Takrur or Tekrour, which flourished roughly parallel to the Ghana Empire. 800: On Christmas Day, Charlemagne is crowned the first Holy Roman Emperor by Pope Leo III. 800: The agriculturally based Buddhist Sailendra kingdom flourishes and declines. (to 832) Inventions, discoveries, introductions Heavy plow in use in the Rhine valley. Horse collar in use in Northern Europe in 8th or 9th century — perhaps introduced from Asia. Mid 8th century – papermaking introduced from China to Arabs. Iron horseshoes came into common use around 770. Pattadakal, Chalukya architecture. The Chinese Buddhist monk Yi Xing applies a clockwork escapement mechanism to operate and rotate his astronomical celestial globe. The first European triangular harp designed by the Picts of Scotland. References 1st millennium 08th century