According to 1985, the gaoyao epitaph unearthed in Turpan recorded the title of Guangde for four years (766), but actually Guangde was only two years old (763-764). In 765, Tang Daizong was changed to Yongtai, and the epitaph still used the title of Guangde, indicating that Tang Jun in the western regions lost contact with the mainland 765 years ago, and the defenders in the western regions still maintained a certain degree.

In the ancient city of Tunguska, Xinhe County, a grain loan deed was unearthed, with the date "Dali 15 years" on it. Another unearthed "Yang Sanniang Loan Contract" was signed in the 16th year of Tang Dali. "Dali" is the title of Li Yu in Tang Daizong, which took only fourteen years. "The 15th year of Dali" should be the first year of Jianzhong (AD 780), which is the title of Tang Dezong Shili. Sixteen Years of Dali was under construction for two years (AD 78 1). In other words, because Tubo captured Hexi and Longyou during this period and competed with Uighur for the Northern Silk Road, the contact between Anxi military and civilians and the mainland was completely interrupted. Anxi Tang Dynasty soldiers and civilians did not know that the year number had been changed to Jianzhong year number, and they still used Dali year number.

1, both of which are cold knowledge.

2. After the Anshi Rebellion, the Tang Dynasty cut off communication with the western regions.

3. The year number has been changed in the Central Plains, but there is still the previous year number in Tangjun, far away in the western regions.

4. It is also regrettable that the Tang Dynasty weakened from the Anshi Rebellion.