Year 640 (DCXL) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. The denomination 640 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 Europe February 27 – Pepin the Elder, Mayor of the Palace of Austrasia, dies and is succeeded by his son Grimoald. He becomes the head of the Frankish household, and the most powerful man in the Frankish Kingdom (approximate date). King Chintila dies of natural causes after a 3-year reign, in which he permitted the bishops wide authority in Hispania, Septimania and Galicia. He is succeeded by his son Tulga, who becomes ruler of the Visigothic Kingdom (approximate date). At the request of Porga of Croatia, one of the first dukes or princes (Croatian: knez) of Dalmatian Croatia, the Byzantine emperor Heraclius sends Christian missionaries to the Croatian Provinces (approximate date). The French city of Lille (according to the legend) is founded by Lydéric. He kills Phinaert in a duel to avenges his parents' deaths (approximate date). Britain King Eadbald of Kent dies after a 24-year reign. He is succeeded by his sons, Eorcenberht and Eormenred, who jointly rule the Kingdom of Kent (now South East England). Hartlepool Abbey in Northumbria (Northern England) is founded. Wooden huts surrounding a church are built in Saxon style. Africa May – Siege of Babylon Fortress: The Rashidun army lays siege to Babylon Fortress in the Nile Delta (near Cairo). The next two months' fighting remain inconclusive, the Byzantines having the upper hand by repulsing every Muslim assault. July 6 – Battle of Heliopolis: The Muslim Arab army (15,000 men) under 'Amr ibn al-'As defeats the Byzantine forces near Heliopolis (Egypt). Amr divides his troops into three parts, surrounding the Byzantines. December 21 – Muslim Arabs capture Babylon after a seven-month siege; during a night assault Arab warriors open the city gates. The Thebaid region (Upper Egypt) is annexed by the Rashidun Caliphate. December 22 – On orders of the Saracen leader, Amar, the Serapeum of Alexandria, containing works that had survived the destruction of the Library of Alexandria, is burned down, along with its collection of 500,000 manuscripts. This story may be apocryphal. Asia Emperor Taizong of Tang begins the military campaigns against the Western Regions states in the Tarim Basin.