What is the difference between the natural environment of the Central Plains two thousand years ago and today?

In recent years, it is generally believed that the ancestors of Hakkas came from the Central Plains and have a history of thousands of years. Sanming Hakka is closely related to the Central Plains, including consanguinity, literature, language, customs, gods and so on. Hakkas are in the Central Plains and take root in Heluo.

Sanming Hakka ancestors came from the northern Central Plains.

It has been recognized that the ancestors of the Hakka people in Sanming came from the Central Plains. Lin Kaiyin, president of Fujian Hakka Association, pointed out: "The population center of the Central Plains moved south. In the process of moving south, some Hakka ancestors entered the border of Fujian, Guangdong and Jiangxi." "Sanming City Records" records: In the first year of Yongjia in the Western Jin Dynasty, "refugees from the Yellow River basin and Guanzhong area took refuge in Fujian, and thousands of refugees moved to Sanming, Jian 'an County to settle down. "Ninghua County Records": "At the end of Jin Dynasty, Han Dynasty and Song Dynasty, the Han people in the Central Plains moved southward three times on a large scale, and some of them who entered Fujian first came to Shibi in Ninghua. "During the Qin and Han Dynasties, there were 200,000 people in Fujian and Vietnam, and only tens of thousands in Sanming. In the Tang Dynasty, Zheng Chen, (80+0 1 189), Wang Chao, Wang (70+5000) and others led troops into Fujian, and the population of Sanming increased greatly, reaching 26,000+060. In the first year of Tianbao in the Tang Dynasty, the population of Ninghua County was only 5,000, and it increased to more than 1 1 1,000 in Baoyu's years. Shibi became the main settlement of Hakka ancestors in the south. Fujian King (939-942) ordered Zou Yongfu to guard Taining County, and he, Liao and Yang became "Kai Taigong". In Song Dynasty, Jianning County became the peak of population and economy in history, with 253 18 households and 128 142 households in the seventh year of Xianchun. Most of the immigrants who entered Mingxi County took refuge in the south because of the turmoil in the north, and a few of them entered the country with official seals. Qingliu County Records: Since the Sui and Tang Dynasties, immigrants from all parts of the north have moved in one after another and merged with the aborigines to form a Hakka settlement.