Foreign invasions have led to the collapse of many dynasties in Chinese history. Such invasions often occurred at times of internal turmoil within the dynasty, which eventually led to its demise. In the last years of the Eastern Han Dynasty, the warlords of the world were divided and fought with each other, and the power of the Eastern Han royal family was weakened, and the puppet emperor Liu Xie ruled it. However, it turned out that there were no foreign invasions during this period. Even during the fall of the Eastern Han Dynasty and the establishment of the Three Kingdoms, foreign tribes did not invade. It was not until the Western Jin Dynasty that the Xiongnu waged war against the Central Plains Dynasty.
For some time before Sun Cao and Liu seceded and established themselves, they each occupied different territories, and Cao Cao's forces were almost all in the north, so his challenges came mainly from the alien races on the northern border. During this period, the alien tribes in the north mainly included the Xiongnu, Wuhuan and Xianbei, and the situation of these three ethnic groups was different. During the reign of Emperor Wu of the Han Dynasty, the Xiongnu had been completely weakened, and even a hundred years later, at the end of the Eastern Han Dynasty, the Xiongnu still failed to fully regain their strength. Although the strength of the Eastern Han Dynasty at that time was not optimistic, it was still capable of fighting the Xiongnu, not to mention that attacking the Xiongnu in the north has always been one of the traditions of the Han Dynasty.
As for the Wuhuan, as early as the Eastern Han Dynasty, some Wuhuan people submitted to the Han Dynasty, and for more than 100 years after that, they existed as subjects of the Han Dynasty and were responsible for garrisoning the frontier. But during the reign of Emperor Ling of the Han Dynasty, Wuhuan rebelled under the leadership of Zhang Chun and Zhang Ju. Gongsun Chan often fought with the Wuhuan army in the Hebei region, and the two sides were incompatible. When Yuan Shao crusaded against Gongsun Zhan, Wuhuan helped with all his might, and then Wuhuan and Yuan Shao formed a connection of interests. However, with Yuan Shao's defeat in the Battle of Guandu and his death soon after, Wuhuan lost his support and was completely defeated by Cao Cao's general Zhang Liao at White Wolf Mountain, and tens of thousands of Wuhuan surrendered, and the Wuhuan clan was no longer a threat after that.
In general, Wuhuan belongs to the category of indecision, always acting in the first place of self-interest. Of all the alien races of the time, they were less threatening. After Zhang Liao defeated Wuhuan, the Wuhuan clan no longer had the ability to compete with the Central Plains forces, and even in the continuous ethnic integration, the Wuhuan clan completely disappeared in the long river of history. As for Xianbei, he was also completely weakened under Cao Cao's blow, and did not dare to have any ambitions for the Central Plains. At the end of the Eastern Han Dynasty, the alien races in the north did not dare to invade the Central Plains, thanks in large part to Cao Cao and his generals. At the same time, Shu Han Xiliang also solved the problem of alien races in the southwest.
Regarding the southwest region where Liu Bei lived, there were mainly two major foreign races, the barbarian and the Qiang, which also clashed with the Han Dynasty. However, due to the remote geographical location, coupled with the gradual decline of the Han Dynasty, the two ethnic groups did not suffer as fatally as the Xiongnu. Although Liu Bei ruled Shu and had a geographical advantage, he still had to guard against foreign attacks. In order to pacify the alien race, Shu Han negotiated with it many times, and although the progress was slow, it achieved remarkable results. For example, the story between Zhuge Liang and Meng Shu is a confrontation between Shu Han and other races.
* describes "Zhuge Liang's Seven Captures of Meng Huo", although this is not the case in history, but Meng Huo did eventually submit to Shu Han and was appointed by Zhuge Liang to the post of Zhongcheng in the imperial history. Meng Shu was the leader of the alien race, and his submission represented the submission of the clan, until Zhuge Liang died, and the alien race in the southwest no longer dared to make waves. In addition to Shu Han, the Xiliang Ma family also contributed to the pacification of the alien races in the west. The location of the Xiliang army, there are barbarians in the south and Qianghu in the north, and the Xiliang army controls the border defense line that is more than 1,000 miles long, and plays a pivotal role in resisting foreign invasions. Soochow solved the problem of alien races in the coastal mountains.
In the southeast, the alien threat faced by the Soochow mainly came from the Shanyue clan, most of whom were distributed along the coast and posed a great threat to the Soochow. The Shanyue people were not actually purely alien like the Xiongnu, but were the product of the continuous integration of various ethnic groups since the Qin Dynasty. By the end of the Eastern Han Dynasty, Shanyue was not much different from the Han people, and some of the clansmen were even Han people who hid in the mountains and forests to avoid paying taxes. After the Sun clan sat firmly in Jiangdong, Shanyue became a major problem for the Sun and Wu regimes. Like Wu Huan, Shan Yue also united with the Yuan clan to wage war against other regimes. For example, in 198, Yuan Shu ordered his generals to unite with Shanyue and wage war against Sun Wu, but was defeated by Sun Ce.
After that, the rulers of the Sun-Wu regime regarded Shanyue as a serious danger and sent troops to suppress it by force many times. When Sun Quan was in power, he ordered Huang Gai, Lü Meng and others to go to the place where the Shanyue people gathered to guard the town to prevent trouble. Sun Quan's conquest of Shanyue lasted for more than 20 years, and although Shanyue was defeated many times, it was never completely pacified. It was not until 234 that Sun Quan appointed Zhuge Ke as a general, and there was a turnaround. Under the leadership of Zhuge Ke, Wu's ** team put the Shanyue people under a general siege, but avoided direct engagement. They waited for the crops to ripen, and then harvested them in one fell swoop, forcing the Shanyue people to leave the mountains in search of reconciliation due to food scarcity. Subsequently, Sun Quan incorporated the adult males of the Shanyue tribe into the army, while the others were incorporated into the common people.
After more than 20 years of continuous conquest, most of the Shanyue people were forced to leave the mountains and become part of the people of Wu. Their arrival has played an important role in the economic development of Jiangnan. At the same time, the sinicization of the Shanyue people also developed rapidly, and until the end of the Northern and Southern Dynasties, the Shanyue people were almost extinct, and only a few records remained. Summary: Although the Central Plains was constantly in turmoil during the Three Kingdoms period, and Sun Quan, Cao Cao, Liu Bei and others were in their own affairs, they never weakened when it came to resisting foreign invasions. Because after all, the struggle between them is only a conflict between the Han people for power, and if they face the invasion of foreign enemies, the nature is completely different.
With the development of history, various ethnic groups are also constantly merging, and those alien races in those years may have disappeared today, or they may have become part of the Chinese nation, and they are also one of the important forces in the development of China today.