They are given the land between the Drava River and the Adriatic Sea for ridding of Avars. The Serbs are allowed to move from their homeland north of the Carpathians to a territory east of the Croats. Heraclius asks Pope Honorius I to send missionaries to both groups. Winter – Heraclius makes an alliance with Tong Yabghu Qaghan, ruler (khagan) of the Western Turkic Khaganate, for a joint invasion of the Persian Empire the following spring. He promises his daughter Eudoxia Epiphania, age 15, in marriage to Tong Yabghu and sends her under escort with wondrous gifts. Europe Arioald succeeds his brother-in-law Adaloald as king of the Lombards, and afterwards Arioald goes insane. Arioald has his wife locked up in a monastery, accusing her of plotting against him with Grasulf II, duke of Friuli (northern Italy). Britain King Edwin of Northumbria defeats the West Saxons under Cynegils, who has tried to thwart the growing strength of Edwin by having him assassinated. Edwin obliges Cynegils to acknowledge Northumbria's supremacy. April 19 – Eanflæd, daughter of Edwin of Northumbria, is born at a royal residence by the River Derwent. She is baptised by Paulinus, bishop of York. Edwin of Northumbria invades the Isle of Man and then Anglesey. King Cadwallon is defeated in battle, and is besieged on Puffin Island. Edinburgh (Scotland) is founded by Edwin of Northumbria (approximate date). Penda becomes king of Mercia (approximate date). Persia Summer – King Khosrau II plans an all-out effort against Constantinople. He returns to Anatolia with two armies of unknown size, presumably more than 50,000 men each. One of these (possibly commanded by Khosrau himself) is to contain Heraclius in Pontus; another under Shahin Vahmanzadegan is defeated by Theodore. Asia July 2 – Li Shimin travels to the Tang capital Chang'an to bid farewell to his younger brother Li Yuanji, who has been given command of a Chinese expedition against the Eastern Turkic Khaganate. Hearing of a plot to murder him, he and a few supporters seize the northern entrance to the emperor's palace. Li Shimin ambushes and eliminates his rival brothers Li Yuanji and Li Jiancheng, in the Xuanwu Gate Incident. September 4 – Emperor Gao Zu abdicates in favor of his son Li Shimin after an 8-year reign. He passes the throne to him (as Emperor Tai Zong). Births April 19 – Eanflæd, queen of Northumbria Balthild, queen of the Franks (approximate