The first point is that the national strength of the Tang Dynasty was very strong, such as the famous "Kaiyuan Shi Sheng" in history. At that time, the national strength of the Tang Dynasty reached its peak, and Xuanzong of the Tang Dynasty vigorously developed the country's economy and culture. So at that time, many foreign businessmen came to the Tang Dynasty to do business, such as some precious things such as jewelry, spices and ivory, and brought them to the Tang Dynasty for trade activities. The fundamental reason is that people were well-off at that time, so they did it.
The second point is the policy relationship at that time. At that time, the Tang Dynasty was the absolute overlord in any aspect, and Xuanzong of Tang Dynasty attached great importance to the development of foreign trade at that time, and people at that time were not very disgusted with the arrival of some foreign businessmen, so it showed a thriving development trend at that time. Because of the policy support, some foreigners would attract more people after making money in the Tang Dynasty, so the Tang Dynasty at that time was very attractive to foreigners.