The Great Wall.
It was the crown jewel of any ancient regime.
For the agrarian civilization of the Central Plains, its greatest enemy had always been the fierce grassland peoples.
Before the Great Wall appeared, Barbarian Cavalry frequently rode south every year to raid and plunder.
And because they were all small cavalry units with tremendous mobility, they would loot and kill, then flee, leaving no way to deal with them.
Not until the Great Wall appeared did it block the trampling of iron hooves.
If the nomadic peoples wanted to raid again, they had to pay an enormous price.
They either had to assault the walls or cross mountains and ridges on foot.
The former required lives piled upon lives, while with the latter, even if they seized something, without warhorses they would only be hunted to death.
Thus, driven by The General Trend, the once-scattered grassland tribes gradually began to unite, eventually forming several powerful alliances and concentrating their strength against the Central Plains states.
Moreover.
Contrary to many people's impressions.
The Great Wall was by no means a waste of manpower and wealth. On the contrary, it represented enormous savings in national defense expenditures.
While reading the Book of Great Sheng, Chen Sanshi had once come across a record from the Kaiyuan era, when an official had calculated an account for the emperor of that time.
The detailed figures were far too cumbersome. In short, the final calculation showed that compared to the money and provisions consumed by keeping vast numbers of soldiers stationed at the border, building the Great Wall cost a full ten times less.
The lands around Poyang were mountainous, with steep and treacherous terrain.
The range cavalry and large armies could advance through was limited, roughly two hundred li, and the Great Wall