Tang unification of the north

Timeline

1. 618–619Guanzhong · ShaanxiAfter proclaiming emperor, Li Yuan first consolidated the Guanzhong base, defeating remnants of Sui forces under Qutu Tong, making the Wei River valley a secure rear base and source of troops for the eastern campaign into the Central Plains.
2. 620–621Central Plains · HenanLi Shimin destroyed Wang Shicheng's Zheng at Luoyang and defeated Dou Jiande's Xia army at Hulao Pass, bringing the Central Plains core under Tang control and decisively advancing northern unification.
3. 622–628Hebei · HebeiAfter Zheng and Xia fell, Dou Jiande's former subordinate Liu Heita rose in revolt; Tang forces spent several years suppressing the remaining separatists in Hebei and Hedong. By the early Zhenguan era, the main northern separatist forces had been cleared.