629 Heraclius restores the integrity of the eastern border of the Eastern Roman (now called Byzantine by historians) empire.
636 Arab forces defeat Heraclius' army in Palestine.
637 The Arabs annihilate the Persians defending Mesopotamia at Qadasiya.
640 The Muslims overrun Byzantine lands in Syria and Egypt.
642 The Byzantines withdraw to Anatolia but are again badly defeated at Nahavend.
by 651 Khazar expansion splits the Bulgars, driving one constituent up the Volga, and two others towards the Danube.
The Kingdom of Mercia takes primacy away from Northumbria in Britain.
The Lombards take Genoa and much of the heel of Italy.
The New Penguin Atlas of Medieval History, Colin McEvedy, pp 30-31
Constans II, Wikipedia
History of the Byzantine Empire, Wikipedia