Who ruled
- Byzantium Heraclius 610–641
- The Göktürk interregnum, 630–682 Ashina Simo 639–643
- Western Göktürk Khaganate Üç Tuğlu Khan 638–642 · Irbis Ishbara Yabgu Khan 639–641
- Xueyantuo Khaganate (Syr Tardush) Yinan Khan 628–645
And beyond the steppe
- China Tang Taizong 626–649
- Iran Sasanian Yazdegerd III 632–651 · Rashidun Umar 634–644
- Korea Goguryeo Yeongnyu 618–642
- Byzantium Heraclian Heraclius 610–641
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)
Tarim and Sogdiana
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The Tang take the kingdom of Gaochang and make it the prefecture of Xizhou
Gaochang · Tarim Basin · Tang
The date from the Turfan documents; the Xin Tang Shu measures Helu's seat from Xizhou
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)
