According to time division:
The early Tang Dynasty (6 18-7 12), from 7 12 to 762, is called the prosperous Tang Dynasty, the middle Tang Dynasty (762-827) and the late Tang Dynasty (827-859).
From the perspective of the emperor's accession to the throne:
Early Tang Dynasty-the first year of Gaozu Wude (AD 6 18) to the first year of Xuanzong (AD 7 12).
In the prosperous Tang Dynasty, from the first year of Xuanzong Kaiyuan (7 13) to the second year of Daizong Yongtai (766).
Mid-Tang Dynasty-From the first year of Daizong Dali (AD 766) to the ninth year of Wenzong Dahe (AD 835).
Late Tang Dynasty-the first year of Wenzong (AD 836) and the fourth year of beloved Zongtianyou (AD 907).