In 219 BC, Qin Shi Huang ordered Tu Sui to lead an army of 500,000 people to divide into five roads, an average of 100,000 per road, one way to attack Dong'ou and Minyue, two to attack South Vietnam, and the other two to attack Xi'ou.
In the first stage, the Guangdong region was quickly conquered, and there was almost no major resistance. In Guangxi, it was fought for six years, and it was at the cost of "hundreds of thousands of corpses and blood" that it was necessary to unify Guangxi and Vietnam. At the beginning of the Southern Expedition to Lingnan, the Qin army occupied the Guangdong region around Panyu and left the army stationed, and in addition, 300,000 Qin troops went west to fight against the local Baiyue in the Guangxi region, although they killed the leader of the Xi'ou tribe, "Translated Song", but the main general Tu Sui was ambushed and killed.
It was not until 214 BC that Qin Shi Huang appointed Ren Huan as the main general and Zhao Tuo to continue to attack the Tribes of Xi'ou and Luoyue in Guangxi, and in the same year, the great cause of pacifying Lingnan was completed, and the entire Lingnan was thus included in the territory of the Qin Dynasty.
Nowadays, we use the current rules of regional division to see that the land of South Vietnam conquered by Qin Shi Huang in those years is actually located in the current two provinces of Guangdong and Guangxi. Unlike others, Chinese mainly named regions in terms of orientation, and large and many areas with the same location will have a geographical feature that connects them together.
The link between Guangdong and Guangxi provinces is a river that runs through the two provinces: the Pearl River.
Compared with other rivers, the geographical label of the Pearl River is particularly prominent. Because, in ancient times, most people would name them according to their own cognition, using a section of the geological plate in which they were located. In the beginning, the Pearl River was also like this, when the Pearl River referred to only a small section of water from Guangzhou to the mouth of the Pearl River.
However, the current Pearl River contains three rivers that flow from different directions and eventually converge to the mouth of the Pearl River. The reason why I want to talk to you about this definition is mainly because I don't want to cause misunderstandings in the following geographical cognition. The Pearl River to be talked about next mainly refers to the last section of the West River, that is, the Pearl River in a broad sense.
For now, the entire pearl river flows in five provinces, and among them, the leftmost tributary originates in Vietnam.
Therefore, from the perspective of numbers, there will always be a kind of Pearl River system that is a river with a particularly wide flow area. From the perspective of the Pearl River area planned by Qin Shi Huang at that time, although the tributaries of the Pearl River system circulated far away, its core area was still in the Liangguang area. If it were not for the fact that there is a small north-south hill running north-south between the two Guangdong areas and between Xiang and Gansu, there will be no intersection between Xiang, Gan and the Pearl River.
However, it is precisely because of the unique structure of nanling that there is a connection between the two major river systems of the Pearl River and the Yangtze River, and a very majestic canal project has been produced between the two regions. It is precisely for this reason that the emergence of this water conservancy project has stabilized the status of the Qin state as the central state. Although this canal was originally built to facilitate war, it also accelerated the process of Huaxia in the Lingnan region and promoted the great integration and development of mainland culture.
Next, let's look at the administrative division between Guangdong and Guangxi, according to what basis, and what is the basis for the division between the two?
From the perspective of the water system alone, it is difficult for us to see the basis of the sub-bureau between the two Cantons. Because there are many tributaries of the Pearl River, covering the north and south, it is necessary to look at the basis between the two from the perspective of the mountain. The terrain of the Liangguang area is not as dense as that of the Fujian region, on the contrary, the entire Lingnan Plate presents a basin-like topography structure with high surroundings and low middle, so this part of the region is called the Guangxi Basin.
The mountains in the lower reaches of the Pearl River are mainly based on the trumpet mouth of the Pearl River and are arranged in a fan-shaped manner, so compared with Guangxi, Guangdong shows a more open state. When it comes to the basin, everyone's impression of the basin should be neatly edged and the hinterland is flat. However, Guangxi is indeed an exception, and the outer edge of the Guangxi Basin is mainly composed of some north-south mountains, so in terms of edges, it is more like a basin with many gaps in the edges.
But it is precisely because of these gaps that the rivers that flow into the Pearl River enter the Guangxi Basin through these gaps, thus rushing out of the relatively independent river valley plains. Therefore, to some extent, it is precisely because of these gaps at the edge of the basin that Guangxi has been achieved.
Moreover, from the perspective of the topography of the two Guangdong regions, guangxi is not necessarily more complicated than Guangdong. Although the mountain mass of Guangxi is larger than that of the western part of Guangdong, if the Guangxi area is not distributed in a basin, it will also form a coastal estuarine plain like Guangdong. In this case, it is even possible to allow the rivers in northern Guangxi to flow into the Pearl River to the east and west, so that the tributaries of the south can be brought together and flow out of the sea.
Looking at the mountains that surround Guangxi into a basin, it is possible that these mountains do not have a big role for Guangdong, but they have a very large and positive effect on Guangxi, which is relatively closed in the region. Because they can not only make Guangxi a coastal province, but also limit the entire Guangxi province to the Guangxi Basin, thus making the territory of the Guangxi Basin even larger.
Although, when Qin Shi Huang prepared to go to South Vietnam, he did not consider these geopolitical issues as our descendants did. However, for Qin Shi Huang, who was eager to expand his political territory, what kind of road to reach South Vietnam more quickly was the biggest problem at that time. With the completion of the water conservancy project between the two regions, the Qin Empire officially became the central state.
At this time, the Qin Empire integrated the entire Yangtze River basin as the core area into the Pearl River, thus allowing itself to choose one of the many battle routes with the least loss and the least consumption to expedition south Vietnam.
It is precisely because of this that the Qin state can take South Vietnam into its own pocket in the shortest possible time.
Resources:
["History, Vol. 113, Biography of South Vietnam", "Geographical Division of the Land of The Two Cantons"]