After Liu Bang established the Han Dynasty, why didn't he go south to unify the Qin Dynasty's hometown with the help of his elite soldiers and generals?

After destroying the Six Kingdoms, Qin Shihuang ordered to go south to conquer Baiyue, and expanded the territory of the Qin Dynasty to today's Guangguang, Yunnan-Guizhou and northern Vietnam. However, at the end of the Chu-Han War, Liu Bang, the emperor of the Han Dynasty, unified the world. Instead of relying on the elite troops and powerful generals of the founding of the country to occupy the southern Qin army, he occupied these territories. Instead, he stationed the Han army in today's Hunan and Jiangxi. A generation no longer advances. Why is this? Where else in the south did the Qin Dynasty set up Nanhai County (most of today's Guangdong), Guilin County (most of today's Guangxi and southwestern Guangxi) and As County (now southern Guangxi and northern Vietnam)? area) and immigrated hundreds of thousands of northern criminals, merchants, and widows. People of low social status at that time integrated with local tribes in order to guard the border and build.

After the death of Qin Shihuang, the Qin Dynasty set off an uprising by Chen Sheng, Wu Guang, Liu Bang, Xiang Yu and others, and the north was in chaos. Seeing the chaos in the world, Nanhai County Lieutenant Ren Xiao came up with the idea of ??independence. However, his health was poor. Therefore, he summoned Zhao Tuo, the prefect of Longchuan, and asked him to send troops to block the road between Lingnan and the Central Plains in order to establish an independent country in the Lingnan region. After Ren Xiao's death, Zhao Tuo was appointed as Nanhai County Lieutenant. According to Ren Xiao's strategy, he killed the main officials of the Qin Dynasty and controlled the situation in Nanhai County with his cronies. Subsequently, he sent troops to seize Guilin County and Xiangxian County, and sent troops to blockade the Hengpu, Yangshan, and Huangxi passes leading to the Central Plains. In this way, the Lingnan region was cut off from the Central Plains region.

After Zhao Tuo learned the news of the demise of the Qin Dynasty, he proclaimed himself King Wu of Nanyue in 204 BC and formally established the Nanyue Kingdom. He followed the Qin Dynasty's system of prefectures and counties, and at the same time established several leaders of the Zhao and Ouyue tribes as princes. He respected the living habits of the tribes in Lingnan, attracted the upper classes of each tribe to participate in political power, encouraged intermarriage between Huaxia and various tribes, and promoted Yue autonomy. He also established good relations with neighboring Minyue, Yelang, Dian and other countries, consolidating South Vietnam's rule in the Lingnan region.