On June 18, 618, Gaozu took the throne, and the Tang Dynasty was established, opening a new age of prosperity and innovations in arts and technology. Buddhism, which had gradually been established in China from the 1st century AD, became the predominant religion and was adopted by the imperial family and many of the common people.
Chang'an (modern Xi'an), the national capital, is thought to have been the world's largest city at the time. The Tang and the Han dynasties are often referred to as the most prosperous periods of Chinese history.
The Tang, like the Han, kept the trade routes open to the west and south. There was extensive trade with distant foreign countries, and many foreign merchants settled in China.
The Tang introduced a new system into the Chinese government, called the "equal-field system". This system gave families land grants from the emperor based on their needs, not their wealth.