Who ruled
And beyond the steppe
- China Tang Taizong 626–649
- Iran Sasanian Yazdegerd III 632–651 · Rashidun Uthman 644–656
- Korea Goguryeo Bojang 642–668
- Byzantium Heraclian Constans II 641–668
Eastern steppe
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Environment · Late Antique Little Ice Age: the cold phase the Altai tree rings define from 536 to about 660 (536–660)
Climate and the steppe empires · First Göktürk Khaganate · Avars
The coldest decade in the Altai is the 540s
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Environment · Lake Telmen stands 4.8 metres above its present level, a humid phase before the drying that follows (600–700)
China
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Economy · The Tang cavalry grows from five thousand horses to more than seven hundred thousand, supplied by the Göktürks (618–650)
