First of all, let's talk about the answer that everyone knows: According to the description in The Journey to the West, Tang Priest's book of customs clearance carried westward is like this:
Emperor Li, the king of the Tang Dynasty in the eastern soil, ordered Master Chen Xuanzang, the holy monk of his royal brother, to go to the Da Lei Yin Temple in the western Tianzhu country to worship the Tathagata Buddha for scriptures. I was invaded by illness, and my soul traveled to the underworld. Fortunately, the number of Yang became longer, and I felt that the ghost king was released back to life, and Chen Shanhui was widely spread, and the Dojo of Death was built. The golden body of avalokitesvara Bodhisattva appeared, indicating that there are Buddhist scriptures in the west, so that you can live in seclusion and detachment. Xuanzang, a master, traveled far through Qian Shan and asked for scriptures. If you cross the western countries, you will not destroy the good karma, and you will follow the instructions. In the thirteenth year of Zhenguan in the Tang Dynasty, it was an auspicious day in autumn. Finally, the seal of the Tang Dynasty was sealed.
what is a customs clearance document? In fact, it is equivalent to a modern passport. In ancient times, transportation was inconvenient, and people who traveled far needed supplies along the way. Since we need supplies, we need to enter the city. And ancient cities all had gates. Without customs clearance documents, who knows where you are from and where you are going? A good citizen or a fugitive?
Tang Priest went to the Western Heaven to learn Buddhist scriptures, which was invited by Li Shimin, Emperor Taizong of Tang Dynasty. In a sense, the royal brother Tang Yan is equivalent to Tang Taizong's personal visit. This identity naturally needs a beautiful and atmospheric customs clearance document, so as not to be abrupt by people who are not smart along the way.
With such a simple sentence, why can the Tang Priest get the courtesy of all countries along the way?
the reason is actually very simple: those who make a strong man will be punished even if they are far away!
the Tang dynasty, especially the period of emperor Taizong, enjoyed a great reputation in the world, and was not generally prosperous.
According to records, people from more than half the world at that time were proud to come to the Tang Empire. Not to mention Chang 'an, the largest city in the world, as the Tang Dynasty Empire. Its prosperity is beyond the imagination of people in remote small countries. This is just like A San always wondering if Shanghai really has no power outage for 24 hours.
Since the fame of the Tang Dynasty Empire has spread far and wide, Li Shimin, as the emperor of the Tang Dynasty, is the peak above the peak.
The "passport" of the Tang Priest clearly says "Master Chen Xuanzang, the holy monk of the Imperial Brother". This is not simple, the emperor's younger brother. Excuse me, how do you react when you meet the younger brother of the President of the United States on the road? It can be said that your reaction is the reaction of countless small countries, ministers and people that Tang Priest met all the way west.
many small countries in the western regions are proud to be associated with the Tang emperor, because the sky is far away but they can't be associated. Even if I can really go to Chang 'an and his party one day, whether I can meet the Emperor of the Tang Dynasty is two different opinions.
Now when the younger brother of the Tang Emperor comes, he not only has no harassment, but also offers money for eating and staying in the hotel. As long as you give yourself a convenience and don't deliberately make things difficult, who wouldn't do such a "accommodating"? Who doesn't want to do it?
Please pay attention to the word "Yu Di". What is this? This is the emperor's brother. Who is behind him? He was the most powerful Tang emperor in the world at that time. Disobeying the royal brother is equivalent to disobeying the emperor of Tang Dynasty. To disobey the Emperor of Tang Dynasty is to be an enemy of the whole Tang Empire. Who dares to take it lightly in the whole world?
Therefore, every small country along the way, no matter the king or the official, regarded the Tang priest as a guest of honor almost without exception. This is the power contained in the word "Yu Di".
and this kind of power is not the kind of naked intimidation in the passport of a certain country. But a very subtle, unobtrusive, but extremely lethal word. These two words, even monsters are a little far away. Otherwise, the Tang Priest was captured by monsters many times. Why has this customs clearance document been intact?