In order to ensure the safety of the Yinshan Market, the Shenlong Department will also explore the terrain of Yinshan, build small fortresses in suitable places, and arrange dozens to a hundred troops on duty.

This kind of similar mission was done several times as early as a few years ago in Liangshan, north of Xiayang and Haoyang, and in the mountainous areas around Shangjun and Xihe. At this time, it is natural to be familiar with the road, and the specific city construction, trade, duty, and balanced development are not a problem.

To the north of Yunzhong County is Tuoba Xianbei, and further north are the Beiding people living in the southern part of Beihai, that is, in the area of Lake Baikal.

The Ding Ling people, also known as Gaoche, Dili and Tiele, lived mainly in the area from Lake Baikal to the Western Regions.

During the Eastern Han Dynasty, a part of the Ding Ling people were still nomadic in the south of present-day Lake Baikal, called North Ding Ling.

Some of them migrated to the Altai Mountains and Tacheng area of Xinjiang today, with Wusun and Cheshi in the south, and Kangju in the southwest. There are also some nomadic herders in the Hexi Corridor since the Jianwu period.

During the two Jin and Northern Dynasties in history, Beiding Ling continued to move south and gradually integrated with the local ethnic groups. After the Battle of Weishui, Ding Lingren Zhai Liao also established a short-lived Zhai Wei regime in Liyang. Since then, it has also been named Tiele in the Sui and Tang dynasties, leaving many traces.

Now the Beiding people often go to the Hetao area to trade, they often live in thick felt tents with obvious characteristics, and generally use high-speed carts, pulling goods and tents to go back and forth between the north and south for grazing and trade.

The reason why Ding Lingren commonly used high carts was because the original pastureland was lush and high, with deep snow and swamps. The use of high-level vehicles in such areas can reduce drag and smooth passage.

In this context, the relatively wealthy and most remote Yunzhong County, the strategic economic position is very important.

Most of Yunzhong County is located in the north of the Yellow River, which is mostly a large plain, with abundant water and grass and many rivers, which can comprehensively develop agriculture and animal husbandry.

Junzhi Yunzhong City is located in the central area, and further northeast to Beiyu County, which is the later Hohhot City. Except for a few county seats, most of them are currently tribal and ethnic branches, and the Han people have basically gone into exile.

In the north, there are many north-south peaks in the Yinshan Mountain Range. The south of the mountain is close to Yunzhong County, and the north of the mountain is cold and windy, and it is completely controlled by the Xianbei people of Tuoba and other departments.

Shuofang, Wuyuan, and Yunzhong counties have already made basic arrangements, while Yanmen and Dingxiang on the east side of Yinshan Mountain have some troubles.

In later generations, the Dingxiang and Yanmen areas were arid and rainless, the vegetation was weak, the population was large, the environment was harsh, the land reclamation area was large, the soil erosion was serious, and the clear river water in the past has become the Yellow River.

Dingxiang, Yanmen and Shangjun have become thousands of ravines, which have been washed away by the rain and shattered.

This place was later called the Loess Plateau, from east to west the loess layer gradually thickened, the larger the particles, and the Taihang Mountains in the east of the state blocked the northwest wind, and the loess transport stopped here.

In other words, Bingzhou is the end of the Loess Plateau, and the soil is delicate and suitable for crop growth. Xiliang to the west of Shangjun also has a very thick loess layer, but the particles are large and coarse.

Loess is an alien soil, which is carried by the northwest wind from Xinjiang and Central Asia for hundreds of millions of years, and the clay under the loess is the local soil, but because the upper part is covered by thicker loess, the rock differentiation is very slow, and the clay layer is very thin, but the water insulation is very good.

There is no clay and no water when digging wells here, the loess has no water barrier, wells tens of meters deep are common, and only low-lying places have shallow water.

Dingxiang and Yanmen in the late Han Dynasty were very different from now, the low hills and hills were overgrown with dense miscellaneous trees, the mountains were overgrown with pines and cypresses, birches, and the low-lying places were full of towering trees.

Even the slopes are overgrown with thorns, and wild peach and apricot trees can be found everywhere. The rivers are crisscrossed, the streams are all over the place, there are many deer and birds, and the resources are abundant.

Only on both sides of the river, near the water source, are there some villages in the form of dock forts, or landlords, large households, or family units live in groups, and there are also several large families living in the village.

In this way, the Xiongnu, Xianbei, Wuhuan, and bandits have some ability to protect themselves when they plunder in the spring and winter, and when they encounter a large number of enemies, they can only flee into the mountains to take refuge, and it is common for villages to be burned and livestock to be robbed.

The inhabitants here live a semi-agricultural and pastoral life, and the plains are sparsely populated, and many people flee to live in the mountains, or live in the dock forts of landlords and local tyrants, cultivate and hunt in the surrounding areas, and pay protection money to the lord's family to survive.

Guo Yi, who ruled Dingxiang and Yanmen, had a tacit understanding of non-aggression with Wuhuan and Xianbei, but local conflicts occurred from time to time, and they could not control the individual behavior of ethnic minorities.

In this region, due to the geographical environment, it is difficult to achieve three crops of corn in two years. However, alfalfa can be grown on a large scale, which is very drought tolerant, improves the soil, and serves as fodder for vegetables and livestock.

Promoting the cultivation of alfalfa in ordinary counties would be impossible because food is far more valuable than alfalfa in this era.

But the Tuntian built by Tong Yuan is different.

Some areas that are not suitable for growing grain, or who cannot meet the ration standards of Tongyuan by growing grain desperately, will definitely not be able to meet the requirements by growing grain on their own. If the requirements cannot be met, there will be no guarantee of combat effectiveness, training and other supporting facilities.

How did Tong Yuan deal with it?

In the area south of Taiyuan and Yan'an counties, there are generally other counties and townships that implement Tuntian in the vicinity, and they produce more grain, so they can be transported directly and according to the quota.

In the farther areas, Tong Yuan made very clever use of the advantages of the overall grain stock, and specially received grain in a certain area in spring and summer, and then purchased grain from the areas close to the tuntian fields in need of grain in the autumn.

For example, in Pingcheng and other places, the tuntian developed animal husbandry and alfalfa cultivation, and a relatively large number of people were involved in engineering construction and military training with a little more frequency. Local cultivation is definitely not enough for one stone of grain and grass per month, let alone one and a half stones of the Tuntian Army.

At this time, every spring and summer, the Xinxi Liangjun will sell grain in Taiyuan County, which not only makes some money, but also enriches the grain circulating in the Taiyuan area. In the autumn, when the price of grain dropped and the circulation was abundant, the Xinxi Liang army would buy a large amount of grain from the Taiyuan area in the south of Yanmen.

These grains were used to supply the military and civilian tuns in Pingcheng and other places in the northern part of Yanmen County to engage in engineering and military affairs. And the purchase price is definitely lower than when it was sold in spring and summer, and the worst is that it is even worth making ends meet.

This trick is actually a specific flexible use of the regular closing position.

Standing positions are generally set up by the government to cope with the shortage of green and yellow in spring and summer, and the soaring food prices. Therefore, the income is low in autumn and sold at a price lower than the market in spring and summer to alleviate the urgency of the people. This measure became permanent for a time, but then gradually stopped because it became a disguised exploitation of the people.

At this time, Tong Yuan did not implement it simply and rudely, but flexibly implemented it in Tuntian, a system where the grassroots strength is the strongest and outsiders cannot interfere.