Why did the Buddhist civilization in the western regions, which lasted for thousands of years, die out?

Let me guess. First, the Western Region is an important part of the Silk Road. With the opening of the Silk Road, commercial exchanges between merchants have been opened, and people from the western regions have scattered everywhere, and their prosperity has passed away and their development has declined. Instead of trying to survive in their own homes, they have gradually disappeared because of the renewal of the times.

Second, because of a cholera, we can see from history that a war can destroy a country and establish a new country and dynasty. If the western regions disappear without a trace because of a war, it is normal, and the winner will rewrite history and annihilate everything.

Thirdly, because the natural environment is very bad, when we watch the TV series "Ghost Blowing Lights", we can find that the beautiful ancient desert in the western regions is very large, the weather is hot, and there is a shortage of water resources. Because of a natural disaster, people are gradually dying, and the civilizations of the Buddhist countries in the western regions are also buried by dust.

Fourth, disease. The medical level in ancient times was not developed. If someone gets some infectious diseases, they will not have the consciousness of seeing a doctor, but will pray to God and worship Buddha to ensure safety. Therefore, a plague or infectious disease may also make the whole country perish.