The west of the river was a battleground for the military, not only did people have to defend the city, but horses also had to defend the city. Even the grass, trees and birds had to do some work, so they couldn't be idle in vain. Although there were solid side walls and strong gates, the enemy could not help invading. Along with the wolf smoke, more troops were immediately dispatched to the city walls, and some facilities were used to block the enemy troops at the military front, maximizing the enemy's combat effectiveness and killing the enemy's prestige.

The Han Dynasty used staghorn wood and iron chestnut antlers, which were set on the road. Regarding iron chestnut antlers, I saw a wicked ghost when I was in town. He secretly sprinkled iron chestnut antlers on the top of Wushuo Ridge. After a passing car had a flat tire, I saw the advertisement sign he put up on the side of the road: Eat, fix tires. He has been fixing tires for many years and should be very rich. However, last year I saw him pick up junk in the county seat. It can be seen that wicked people cannot get rich.

Hexi produces a kind of grass called tribulus terrestris, which is abundant in the desert, and its whole body is covered with sharp thorns that hurt people. There is also a kind of grass called Zhang Gongdao, which has three thorns, and one thorn stands up on either side, which is very fair, which is much sharper than tribulus terrestris.

Collect these things and sprinkle them on the enemy's way to reduce and disperse the pressure given by the enemy during the siege. In summer, the Xiongnu people do not like to wear shoes, and they go to war barefoot. When they meet on a narrow road, thistles win. The sharp thorns of these plants pierce the soles of the feet of the people and horses, and it hurts to scratch their hearts. The army and horses moved forward, and the wounded held their feet to pick up the thorns. The Xiongnu probably put on their shoes because they were afraid of thistles. They can't make straw shoes, they can't make cloth shoes, but only cowhide boots and cowhide soft shoes. The soles are cut out of thick cowhide, and the soft cowhide is made into shoe hooks and tied with thin straps of cowhide. There are also dogs, which

In the field, if there are not enough grass thistles, it is necessary to make iron chestnuts and cut wood thistles. You also need to make wooden rakes. The enemy steps on the head of the rake with one foot, chops, the handle of the rake is upturned, and a stick is stuffed. Go down. There are also large wooden rakes to deal with horses. When a horse falls down, a piece falls behind it. In the mountains, there are also iron hook locks and tripwires, all of which are used against cavalry. Among the Xixia weapons unearthed in Hexi is a kind of fired porcelain, called porcelain thistles, like a hedgehog, filled with gunpowder in the middle, which is used as a bomb.

There is another kind, the people of my village call the evil hooves. All kinds of long thorn branches, black thorns, white thorns, hairy grass, block the pass. Arrows were fired at the city wall, and the enemy cavalry cannot pass the pass smoothly. There is also a fence near the city gate. Horses are very spiritual. When they see thorn branches all the way, they are afraid of getting their hooves pierced, and they wander and stagger. In this way, the pressure of siege can be relieved.

In ancient castles, large flocks of birds can be seen perched on buildings everywhere. The roofs of the temples and behind the plaques are their nests. They go to the outside of the city forage in the morning and return to the nest in the evening. If the city is besieged and the enemy cannot be driven away, these birds can be used. First capture the birds in the city in the dark and starve. Prepare to empty the core and stuff it with burning wormwood as kindling. As soon as the sun comes out in the morning, the birds have the habit of going out of the city forage. Because they are hungry, they fly all the way to the enemy's granary outside the city. Birds know where there is food. In this way, the birds carrying fire seeds can almost set fire to the granary outside the city and retreat from the enemy. If it was a bird outside the city, it could be caught during the day and released at dusk, or the granary could be set on fire. Experts were among the people, and some people even knew the flight route of the birds.

When there is war, ecological destruction is inevitable. Building, felling, river diversion, burning. The ecology in the west of the river is fragile and cannot stand the tossing. The castle oasis slowly disappears in time, and a tragic battle must lurk beneath a deserted castle. Gelding City, Locking Sun City, Blackwater City, Broken City, Camel City... What we can find today is only the broken walls, and the immortal is the loess cement, which still tells history in a sad and heavy manner.