|Covid-19|Spring – Byzantine–Sassanid War: Emperor Heraclius issues an ultimatum for peace to King Khosrow II, but he refuses his generous terms. The war-weary Persians revolt against Khosrow's regime at Ctesiphon, and install his son Kavadh II on the throne on February 25. He puts his father to death and begins negotiations with Heraclius. Kavadh is forced to return all the territories conquered during the war. The Persians must give up all of the trophies they have captured, including the relic of the True Cross. Evidently there is also a large financial indemnity. Having accepted a peace agreement on his own terms, Heraclius returns in triumph to Constantinople.
Third Perso-Turkic War: The Western Göktürks, under their leader Tong Yabghu Qaghan, plunder Tbilisi (modern Georgia). The Persian defenders are executed or mutilated; Tong Yabghu appoints governors (tuduns) to manage various tribes under his overlordship.
Battle of Cirencester: King Penda of Mercia defeats the West Saxons at Cirencester (south-west England), in what later will be Gloucestershire. After reaching an agreement, he takes control of the Severn Valley and the minor kingdom of the Hwicce.
February 25 – Khosrow II, the last great king of the Sasanian Empire, is overthrown by his son Kavadh II.
September 6 – Ardashir III, age 7, succeeds his father Kavadh II as the twenty-fourth king of the Sasanian Empire, on the latter's death from plague.
Muhammad, Islamic prophet, leads about 1,400 men on a pilgrimage to Mecca, where their passage is blocked. The Quraysh tribe and the Muslim community in Medina sign a 10-year truce (Treaty of Hudaybiyyah).
Indian astronomer Brahmagupta writes the Brāhmasphuṭasiddhānta, an early, yet very advanced, mathematics book, including rules for computing with zero.
The Sharia enjoins women as well as men to obtain secular and religious educations. It forbids eating pork, domesticated donkey, and other flesh denied to Jews by Mosaic law (approximate date).
Muhammad's letters to world leaders explain the principles of the new monotheistic Muslim faith, as they will be contained in his book, the Quran.
Adomnán, Irish abbot and hagiographer (d. 704)
Benedict Biscop, Anglo-Saxon abbot (d. 690)
Gao Zong, emperor of the Tang dynasty (d. 683)
John Maron, Syriac monk and patriarch (d. 707)
January 22 – Anastasius of Persia, monk
February 28 – Khosrow II, king of the Persian Empire
April 15 – Empress Suiko of Japan
June 3 – Liang Shidu, rebel leader
Babai the Great, church father and theologian
Du Yan, chancellor of the Tang dynasty
Kavadh II, king of the Sasanian Empire
Li Dashi, Chinese official and historian (b. 570)
Shirin, wife of Khosrow II (approximate date)
Suibne Menn, High King of Ireland
Theodelinda, queen of the Lombards
Tong Yabghu Qaghan, ruler of the Göktürks
Year 628 (DCXXVIII) was a leap year starting on Friday (link will display the full calendar) of the Julian calendar. The denomination 628 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.