WHEN LI YUAN, posthumously known as Gaozu, proclaimed the Tang dynasty in 618 CE and made himself first emperor of the new dynasty, there was little to indicate that this would become one of the most celebrated dynasties of Chinese history. The Tang would last officially until 907, and the legal and political institutions created during this time, as well as many forms of cultural achievements, would influence the development of East Asian history for centuries to come. Yet, in 618, the only example of a dynasty whose rule spanned many generations and covered a large territory was the Han (206 BCE– 220 CE). The Tang's immediate predecessor, the Sui dynasty (581– 618 CE) had succeeded in overcoming the territorial disunion which for centuries had split the former Han empire into a northern and southern part, each ruled by a succession of dynasties, which often lasted only a couple of generations. For the rulers and subjects of the newly founded Tang dynasty there was no way to know if this dynasty, too, was to disintegrate in the course of a few decades, or if it would break that cycle. And, throughout the nearly 300 years of the Tang dynasty's lifespan, there were moments of crisis that imperilled the continuity of the ruling house. Nevertheless, the Tang somehow survived multiple moments of danger until its last emperor was forced to abdicate in 907, and is throughout East Asia remembered as a reference point of political power and high culture, which left an enduring influence on Korean, Japanese, and Vietnamese states.

The Tang dynasty thus neatly spans the period defined in this volume as “Early Middle Ages,” but this suggests the dynasty was only at the beginning of the Middle Ages as a longer historical period. From East Asian history's point of view, it may better to see the Tang's cultural, economic, social, and political life as the culmination of traditions that developed over centuries from the late third century BCE in the early empire (Qin and Han dynasties, 221 BCE– 220 CE) through what is now among China historians sometimes called the “early medieval” period between the Han and Tang. Furthermore, traditional dynastic divisions mask continuities on all levels, due to the singular focus on the ruling clan, a shortcoming that is also evident when looking towards the end of the Tang and what followed.