I don't buy that. China today can thanks the Mongol and the Manchu for maintaining and enlarging Chinese territory. China indigenous culture never disappear Take the mongol Kublai Khan is educated by the Chinese tutor and well versed in Chinese literature and history He founded what is now known as Beijing opera and built theater all over Beijing to popularize the beijing opera. I would say the infusion of energetic Nomad blood invigorate the Chinese nation that is why they last so long Thru the history the Han always absorb foreign culture and blood eg Chu, Wu(Hubei, Anhui), Yue(Fujian south Zhejiang), Lingnam(Guangdong, Guangxi)
A lot of genetic disease are cause by inbreeding having diversity in DNA ward of those disease
He even fight his own brother Arieq Khan exactly because He left the mongol way of life and adopt Chinese culture and way of life Some of the great Mancu emperor like Qianlong and Kangshi are great lover of Chinese culture
Kublai had access to supplies from the fertile lands of China, while Ariq Böke had to import resources to Karakorum in the semi-arid steppes.
Kublai Khan depended on these supplies from China and therefore needed Chinese popular support to win the civil war.
Kublai ingratiated himself to his subjects with the help of his Chinese advisers. He presented himself as a sage emperor capable of uniting the Chinese, Korean and his fellow Mongols. While calling out Ariq Böke as a destructive usurper.
Kublai promised to reduce taxes, modeled his government institutions to resemble those of the Chinese dynasties, and adopted the
of
Zhongtong, which means "moderate rule".
His policies were popular in northern China, but had no impact on his relations with the Southern Song. The Song invaded while Kublai was preoccupied with the civil war, and recovered territory previously lost to the Mongols.
Kublai dispatched a diplomat, Hao Jing, to discuss the prospects of a peaceful resolution to the war with the Southern Song. The Song, however, rejected Kublai's overtures and imprisoned Hao for the next decade.