The place where litchi grows hasn't changed since the Tang Dynasty, has it?

There is another change, which is caused by climate change. The following article explains it in detail.

From the end of the Tang Dynasty to the present, it has been inconclusive where the lychee that Yang Guifei ate came from. Generally speaking, there are three kinds of sayings, namely Lingnan (Guangdong and Guangxi) and Fujian, Sichuan and Chongqing. Many scholars have had a heated debate on these three viewpoints. However, they all ignored an important factor-climate change once caused great changes in the distribution area of litchi.

Litchi is a typical evergreen fruit tree in the south subtropical zone. Litchi is not tolerant to low temperature and frost in winter, and the temperature requirement for survival is that the annual average temperature is above 65438 08℃; If it is below 2℃ in winter, it may suffer from freezing injury; Below 0℃, the shoots will freeze to death; At MINUS 2℃, the whole litchi tree will freeze to death. Because of this characteristic of litchi, many scholars often take the distribution change of litchi as the basis when studying paleoclimate change. For example, Zhu Kezhen, the founder of meteorology in China, took the distribution changes of litchi recorded in historical books as an important basis for analyzing historical climate changes in his Preliminary Study on Climate Change in China in the Last Five Thousand Years.

Paleoclimatologists have clearly confirmed that in the early Tang Dynasty, the climate in China was generally warmer than it is now. Zhu Kezhen pointed out that during the Sui and Tang Dynasties, the climate was warmer than in modern times. In the winters of 650, 669 and 678, there was no ice and snow in Chang 'an, and plum trees grew longer than in the palace (plum trees can't grow in winter in Xi now), which fully shows that the temperature at that time was higher than now. As far as Sichuan Basin is concerned, the temperature in the Tang Dynasty was about 2℃ higher than it is now, and the surrounding mountains blocked the invasion of cold air in winter, making the climate conditions in most parts of Sichuan Basin suitable for the growth of litchi. This is also clearly recorded in the literature, such as Pingchang County, Bazhong City, Sichuan Province, where litchi was planted in the Tang Dynasty. In the Northern Song Dynasty, the climate in Sichuan changed little compared with that in the Tang Dynasty. According to the documents of the Northern Song Dynasty, litchi was widely planted in Sichuan at that time, and a large number of litchi was planted in Chengdu, Meishan, Leshan and Yibin.

At the end of the Northern Song Dynasty and the beginning of the Southern Song Dynasty, the climate in China suddenly became cold. One of the reasons for the demise of the Northern Song Dynasty was that the cold climate significantly reduced the productivity of the northern grasslands, and the northern nomads were seriously short of food, so they went south to seize territory on a large scale. Lan Yong, a professor of historical geography at Southwest Normal University, studied various historical documents and came to the conclusion that there were many fruits and good quality of litchi in the Three Gorges area in the early Southern Song Dynasty 1 167; Only a few years later,1170-172 years later, the climate suddenly turned cold, and the Three Gorges area was covered with snow for three consecutive years. Historical documents not only recorded the cold situation in the Three Gorges area at that time, but also recorded the fact that other places suddenly became cold. For example, according to historical documents, there was a thick ice layer in Taihu Lake at that time, and military horses could walk on the ice. Other materials found in Zhu Kezhen also show that 1 178 litchi trees in Fuzhou were frozen to death in a large area.

It can be inferred that litchi was widely distributed in Sichuan Basin in Tang Dynasty, and many areas around Chengdu were rich in litchi. At the end of the Northern Song Dynasty and the beginning of the Southern Song Dynasty, the climate in China suddenly became cold, and the average temperature in most parts of Sichuan Basin dropped by about 2℃, especially in winter when the temperature was lower than 0℃, which made litchi originally distributed in a large area of Sichuan disappear because of the low temperature. At present, the distribution area is only a small part of Hejiang County, Sichuan Province, so the history of planting litchi in Sichuan is gradually forgotten.

Although there is no clear record in the literature, we can boldly infer that the litchi eaten by Yang Guifei is far more likely to come from Bashu than from Lingnan. At that time, litchi was widely distributed in Sichuan basin, with good quality and close to Chang 'an. At that time, the transportation speed was as high as 500 miles per day, and it could be reached in two days by mail, which could completely reach Chang 'an during the preservation period of litchi. Therefore, there is no reason for people to go further and further and transport litchi from the distant Lingnan to Chang 'an.