645

645 in various calendars
Gregorian calendar	645; DCXLV
Ab urbe condita	1398
Armenian calendar	94; ԹՎ ՂԴ
Assyrian calendar	5395
Balinese saka calendar	566–567
Bengali calendar	52
Berber calendar	1595
Buddhist calendar	1189
Burmese calendar	7
Byzantine calendar	6153–6154
Chinese calendar	甲辰年 (Wood Dragon); 3342 or 3135; — to —; 乙巳年 (Wood Snake); 3343 or 3136
Coptic calendar	361–362
Discordian calendar	1811
Ethiopian calendar	637–638
Hebrew calendar	4405–4406
Hindu calendars
- Vikram Samvat	701–702
- Shaka Samvat	566–567
- Kali Yuga	3745–3746
Holocene calendar	10645
Iranian calendar	23–24
Islamic calendar	24–25
Japanese calendar	Taika 1; (大化元年)
Javanese calendar	536–537
Julian calendar	645; DCXLV
Korean calendar	2978
Minguo calendar	1267 before ROC; 民前1267年
Nanakshahi calendar	−823
Seleucid era	956/957 AG
Thai solar calendar	1187–1188
Tibetan calendar	阳木龙年; (male Wood-Dragon); 771 or 390 or −382; — to —; 阴木蛇年; (female Wood-Snake); 772 or 391 or −381

Millennium:	1st millennium
Centuries:	6th century; 7th century ; 8th century;
Decades:	620s; 630s; 640s ; 650s; 660s;
Years:	642; 643; 644; 645 ; 646; 647; 648;

Year 645 (DCXLV) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. The denomination 645 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

Alexandria revolts against Arab rule at the appearance of a Byzantine fleet, (300 ships^[1]) and Byzantine forces recapture the city. Abdullah ibn Sa'ad, Arab governor of Egypt, mounts an assault and retakes it. He begins building a Muslim fleet.

Plato, exarch (imperial governor) of Ravenna, invades the southern Po Valley. The Lombards under King Rothari defeat him on the banks of the Panaro River (near Modena); 8,000 imperial troops are killed.

King Cenwalh of Wessex (according to Bede) is driven from his kingdom by his brother-in-law, King Penda of Mercia. He flees to the court of king Anna of East Anglia, and is baptised while in exile. Penda overruns Wessex.
Gwynedd and much of Wales is in the grasp of famine. Would-be king Cadwaladr Fendigaid flees to Brittany. Civil war continues in his kingdom (approximate date).

July 10 – Isshi Incident: Prince Naka-no-Ōe and Fujiwara no Kamatari assassinate Soga no Iruka, during a coup d'état at the imperial palace.
Empress Kōgyoku is forced to abdicate the throne in favor of her younger brother Kōtoku, age 49, who becomes the 36th emperor of Japan.
Naka-no-Ōe becomes crown prince and prime minister. Supporters of the semi-legendary regent Prince Shōtoku gain supremacy in Japan.
Emperor Kōtoku establishes the Taika Reform: a land reform based on Confucian ideas and philosophies from China (approximate date).
Kōtoku creates a new city at Naniwa, and moves the capital from Yamato Province. The capital has a sea port, establishing foreign trade and diplomatic relations.

Goguryeo–Tang War: A Chinese expeditionary army under Emperor Taizong crosses the Liao River into Goguryeo (One of the Three kingdoms of Korea).^[2]
July 18 – Tang forces under Li Shiji heading southeast, toward the Yalu River, put the strategic fortress city of Ansi (Liaoning) under siege.
September – Taizong is unable to capture Ansi fortress defended by Korean general Yang Manchun. Food supplies running low, he withdraws his forces.^[3]

Xuanzang, Chinese Buddhist monk, returns to China after a 16-year pilgrimage to India. He is greeted with much honor by Emperor Taizong.
The Giant Wild Goose Pagoda at Ci'en Temple, Xi'an (Shanxi) is first erected during the Tang Dynasty (approximate date).

^ The Caliphate Its Rise, Decline and Fall. Conquest of Egypt, Chapter XXII (p. 166)
^ Graff, David A. (2002). "Medieval Chinese Warfare, 300–900". London: Routledge, p. 197. ISBN 9780415239554
^ Lee, Kenneth B. (1997). Korea and East Asia: "The story of a phoenix". Westport: Praeger. p. 16. ISBN 9780275958237.