Who ruled
- Byzantium Heraclius 610–641
- First Göktürk Khaganate Ilig Khan 620–630 · Töles Khan 620–630
- Western Göktürk Khaganate Tong Yabgu 618–630 · Baghatur Khan 628–630 · Si Yabgu Khan 628–632
- Xueyantuo Khaganate (Syr Tardush) Yinan Khan 628–645
And beyond the steppe
- China Tang Taizong 626–649
- Iran Sasanian Khosrow II 591–628 · Kavad II 628–628 · Ardashir III 628–630
- 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)
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Töles submits to the Tang on 21 April; the Xueyantuo secede from Ilig as a khaganate of their own
Ilig Khan · Xueyantuo Khaganate (Syr Tardush) · Tiele · Defection of Töles (628)
Also dated 629 (Jiu Tang Shu 194上): 三年，薛延陀自稱可汗於漠北: the khan's self-proclamation in the third year of Zhenguan; the risings north of the Yinshan are in the first year, 627.
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)
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Taizong refuses to rebuild the Long Wall against the Göktürks and names the signs of their coming ruin
Taizong's Speech on the Signs of Ruin (628) · Tang · Ilig Khan
Persia
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Khosrow II is deposed and killed by his own nobles; four years of disputed succession follow
