How did the emperors in the prosperous Tang Dynasty make the Tang Dynasty prosperous?

In the Tang Dynasty, overseas trade began to flourish. In the second half of the eighth century, it entered the Indian Ocean from Guangzhou via the Straits of Malacca and arrived in India. By the Tang Dynasty, the scope of overseas traffic reached most of the old world, Ceylon, and then westward into the Persian Gulf, Aden and the Red Sea. Comparing the sea lanes to the west with those to Silla and Japan, Middle Eastern businessmen such as Jews, Persians and Arabs came to the East one after another. China coastal cities such as Jiaozhou, Guangzhou, Quanzhou, Mingzhou (now Ningbo, Zhejiang) and Yangzhou have mushroomed and become important foreign trade ports due to frequent exchanges with foreign ships. In order to cope with the new situation of maritime trade, the Tang Dynasty also set up a special "city envoy" to manage the entry and exit of ships and the reasons for taxation. Since then, the volume of overseas trade has been increasing.