Year 720 (DCCXX) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar. The denomination 720 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Byzantine Empire Summer – Emperor Leo III secures the Byzantine frontier, by inviting Slavic settlers into the depopulated districts of the Thracesian Theme (western Asia Minor). He undertakes a set of civil reforms, and reorganizes the theme structure in the Aegean region. Leo's 2-year-old son Constantine V is associated on the throne, and married to Tzitzak, daughter of the Khazar ruler (khagan) Bihar. Europe Umayyad conquest of Gaul: Governor Al-Samh continues his campaign; he makes Narbonne the capital city of Muslim Septimania (Southern France), and uses it as a base for razzias. King Ardo is killed, and becomes the last ruler of the Visigothic Kingdom of Hispania. Some Visigoths refuse to adopt the Muslim faith, and flee north to Aquitaine. This marks the end of the Visigothic Kingdom. Muslim forces under Al-Samh begin the prolonged siege of Carcassonne, a fortified Visigothic town located in the Languedoc-Roussillon. Britain King Ine of Wessex builds a stone church at Glastonbury Abbey in Somerset (approximate date). Arabian Empire Umayyad conquest of Transoxiana: The first Turgesh attack on Muslim-Arabs in Transoxiana leads to the siege and relief of the Umayyad garrison at the fortress of Qasr al-Bahili, near Samarkand (or 721). Yazid ibn al-Muhallab, former governor of Iraq, revolts and is defeated at Basra, by Umayyad forces under Al-Abbas ibn al-Walid and Maslama ibn Abd al-Malik. He is arrested and later executed. February 10 – Caliph Umar II is poisoned by a servant, and dies in Aleppo (Syria) after a 3-year reign. He is succeeded by his cousin Yazid II. The Umayyad Caliphate reaches its greatest extent in Spain, controlling all of it except a small region in the north controlled by the Kingdom of Asturias. Asia In the Chinese capital of Chang'an, the walls of a gated city ward collapse during the night, which unexpectedly forms a large pool out in the open. This is most likely caused by a sinkhole created when ground water eroded the limestone bedrock beneath. As a consequence of this, more than 500 homes are destroyed (approximate date). Americas The Third Tikal-Calakmul War begins. By topic Literature