Year 622 (DCXXII) was a common year starting on Friday (link will display the full calendar) of the Julian calendar, the 622nd year of the Common Era (CE) and Anno Domini (AD) designations, the 622nd year of the 1st millennium, the 22nd year of the 7th century, and the 3rd year of the 620s decade. The denomination 622 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.
|Ab urbe condita||1375|
|Balinese saka calendar||543–544|
|Chinese calendar||辛巳年 (Metal Snake)|
3318 or 3258
— to —
壬午年 (Water Horse)
3319 or 3259
|- Vikram Samvat||678–679|
|- Shaka Samvat||543–544|
|- Kali Yuga||3722–3723|
|Minguo calendar||1290 before ROC|
|Seleucid era||933/934 AG|
|Thai solar calendar||1164–1165|
748 or 367 or −405
— to —
749 or 368 or −404
- Byzantine–Sasanian War: Emperor Heraclius sails from Constantinople with an expeditionary force (probably 50,000 men), and starts a counter-offensive against the Persian Empire (his young son, Constantine III, is left behind as regent under the charge of Sergius I, patriarch of Constantinople, and patrician Bonus). He lands a few days later at the junction of Cilicia and Syria, near Alexandretta and ancient Issus.
- Battle of Issus: Heraclius defeats the Persian forces under Shahrbaraz in Cappadocia. He recaptures Anatolia, but returns to Constantinople to deal with the threat posed to his Balkan domains by the Avars, and puts the Byzantine army into winter quarters in Pontus.
- The Western Turks conquer the Oxus valley and cooperate with Heraclius against Persia, taking Khorasan (modern Afghanistan).
- September 9 or June 17 – The Islamic prophet Muhammad, after being warned of a plot to assassinate him, secretly leaves his home in Mecca to make the Hegira (emigrate) to Yathrib (later renamed by him Medina), along with his companion Abu Bakr. They take refuge in the Cave of Thawr south of Mecca for three days, departing on September 13 or June 21.
- September 20 or June 28 – Muhammad does not enter Yathrib directly, but stops at its outlying environs of Quba. He establishes the Quba Mosque here, the first mosque of Islam. On July 2 (or September 24) he makes his first visit to Yathrib for Friday prayers.
- October 4 or July 13 – After a fourteen days' stay in Quba, Muhammad finally moves from Quba to Yathrib, and is greeted cordially by its people. Here he drafts the Constitution of Medina, an agreement between the various Muslim, Jewish, Christian and pagan tribal communities in the city, forming the basis of a multi-religious Islamic state, and begins construction of the Al-Masjid an-Nabawi Mosque. Later during the caliphate of Umar in 638, the lunar year during which the emigration to Medina occurred (Friday 16 July 622 – 4 July 623) is designated "Year One" of the new Hijri era (Anno Hegirae – AH).
- Xuanzang is fully ordained as a Buddhist monk at the age of 20.
- April 8 – Shōtoku, prince and regent of Japan (b. 574)
- Andronicus, Coptic Orthodox Patriarch of Alexandria
- Colmán mac Cobthaig, king of Connacht (Ireland)
- John of Biclaro, Visigoth chronicler (approximate date)
- Li Zitong, rebel leader during the Sui dynasty
- Lin Shihong, rebel leader during the Sui dynasty
- Liu Wuzhou, rebel leader during the Sui dynasty
- Walid ibn al-Mughirah, chief of the Banu Makhzum clan of the Quraysh tribe.
- Kaegi, Walter Emil (2003). Heraclius: Emperor of Byzantium. Cambridge University Press. p. 116. ISBN 0521814596.
- Shamsi, F. A. (1984). "The Date of Hijrah". Islamic Studies. 23: 189–224, 289–323.
- Shaikh, Fazlur Rehman (2001). Chronology of Prophetic Events. London: Ta-Ha Publishers. pp. 51–52.
- Howgego, Raymond John (2003). Encyclopedia of Exploration to 1800. Hordern House. p. 522. ISBN 978-1-875567-36-2.
- Illustrated Dictionary of the Muslim World. Marshall Cavendish. 2010. pp. 122–123. ISBN 978-0-7614-7929-1.
- DeBlasi, Anthony (2002). Reform in the balance: the defense of literary culture in mid-Tang China. SUNY Press. p. 170. ISBN 978-0-7914-5436-7.
- The New Encyclopædia Britannica: Micropædia (15th ed.). 1991. p. 765. ISBN 978-0-85229-529-8.
- Holtzclaw, R. Fulton (1980). The Saints Go Marching In. Keeble Press. p. 24. ISBN 9780933144002.
- Woo, X. L. (2008). "622&pg=PA19 Empress Wu the Great: Tang Dynasty China. Algora Publishing. p. 19. ISBN 978-0-87586-660-4.