The Xiongnu invasion lasted for a month, and no one knows how many tragedies occurred during this month.

However, no matter how much the Huns robbed, it would not be enough for them to consume, so they still needed to obediently come to Zhang Yu to be slaughtered.

After the pooling of their tribes, and the wealth they had plundered, they had not yet gathered all the food they had.

In the end, they could only exchange some of their horses with Zhang Yu.

Zhang Yu is still very short of horses, and this time he can get tens of thousands of war horses, and this deal is still very cost-effective.

This time, the Xiongnu asked for a very large amount of goods, and in addition to the relatively low profit on grain, some other commodities were simply huge profits.

With millions of transactions, Zhang Yu and they can earn at least half.

However, most of them are exchanged for materials, and there are not many that are actually traded with copper coins.

By the time the deal was completed, it was already winter, and it was snowing heavily in the north, making it uncomfortable for people to be outside, let alone fighting.

Zhang Yu did not take it with him in Shenyang City, but in Yuxian County, in the place of present-day Dalian.

"The volume of trade is so great that this money has become a constraint on trade." After Zhang Yu's research, he found a big problem.

There are two problems, one is that with the development of commerce and the gradual increase in trade volume, hundreds of thousands of copper coins are very cumbersome and inconvenient to transport.

The second problem is that there are not enough copper coins circulating in the market, which restricts business development.

Two questions, Zhang Yu began to think about it.

Both problems can be solved together.

"Minting silver and gold coins can solve the problem of inconvenient transportation, and minting more copper coins can solve the problem of insufficient coins in circulation."

Zhang Yu thought of coinage.

I didn't dare to do it before, because the Han was still there, and coinage was a rebellion.

Now that the Han Dynasty has existed in name only, no one will care about the coinage.

Therefore, Zhang Yu planned to start minting coins.

To mint a coin, you need to have copper, gold, and silver.

Although Zhang Yu found some mines, the reserves were not very large.

The next thing Zhang Yu has to do is to find someone to go to prospecting, and only enough ore can mint enough coins.

Then there is the need to decide on a template.

It is not difficult to find someone to make the template, and the most important thing is that Zhang Yu has a system, the system can be exchanged for a forging press, although it is small, but it is no problem to mint coins.

Previously, Zhang Yu had already exchanged the forging press to forge equipment, especially armor, and he needed the forging press even more.

Now it's just right to exchange some more to mint coins.

Gold coins and silver coins are easy to do, Zhang Yu made a template by himself, and determined the value of gold and silver coins.

But copper coins are a bit tricky.

Others who forge copper coins that are different from the copper coins circulating in the Han Dynasty may not accept it, and Zhang Yu, who casts the same, does not have a template on his hand.

Although the imitation template can also be, maybe it can be fake, but the fake is fake, if it is used by someone with a heart, then Zhang Yu's territory may set off a financial crisis, and the market will be chaotic.

So Zhang Yu didn't want to take this risk.

There is no good way to solve it for the time being, so Zhang Yu will do what can be done first.

He found Gu Yong.

"Yuan sigh, there must be relatively large mines in Liaodong or Xuanwu County, you organize more people to explore and mine, even if the land under our control is turned over little by little, we must find enough mines." Zhang Yu said to Gu Yong.

In ancient times, prospecting was very difficult, and Gu Yong's face was difficult.

"My lord, we don't have a dedicated prospector, I'm afraid we won't be able to find the ore in a short time."

Gu Yong didn't agree with Zhang Yu's approach, so he said so.

Because of the use of large-scale personnel to find ore, and then mint the ore into copper coins, the cost is huge, maybe the minted copper coins are not enough to return to the cost, and there is a high possibility of loss.

If these manpower are used to build development, the effect may be better.

Zhang Yu didn't explain too much to Gu Yong, and directly gave him a death order.

If there is not enough money, it will cause deflation and be detrimental to the economy.

These theories of later generations are explained to an ancient.

Gu Yong could only follow the order.

Zhang Yu also wrote a letter asking Zhang Zhao to look for ore in Huiji County.

Zhang Yu knew that there were a large number of silver mines on the islands in Southeast Asia, and he knew the approximate location, so he asked Zhang Zhao to arrange a large number of people to find them, and once they found them, they would send them.

After doing this, Zhang Yu had to think about how to mint copper coins.

The copper coins minted by themselves are not recognized by others, and they will be invalidated when the time comes, and the imitation of the copper coins that are now commonly used will be discovered by others, and the time will cause a crisis.

"It's better to mint copper coins myself to be safe, it's a big deal to circulate internally, and if I can legalize these copper coins, then I can use them elsewhere when the time comes."

Zhang Yu began to plan, and the minting of copper coins was as important as printing money in later generations.

Legal issues can be solved slowly, and Zhang Yu will put up the shelves first.

He immediately arranged for people to start setting up a workshop, and the gold and silver coins were minted online along with the copper coins.

"Let the Queen Mother make a decree, as long as you find Liu Xie again and ask him to get a holy decree, my copper coins will be legalized, and they can be used elsewhere at that time."

Zhang Yu had already thought of a way, but Liu Xie was nowhere to be found at this time.

At that time, Zhang Yu was fighting with Wu Huan, and he didn't care about this.

In history, Liu Xie fled to Luoyang and was picked up by Cao Cao, and now Luoyang is Liu Bei's territory, Liu Bei claims to be a relative of the Han family, and Liu Xie is likely to defect to Liu Bei.

At this time, Zhang Yu opened up first, and talked about other things later.

After everything was done, Zhang Yu was going to start collecting accounts again.

At the beginning, all the people who participated in the siege of Huiji County did not pay.

Yuan Shao, Liu Bei and other Zhang Yu had no way to take them for the time being.

But at the beginning, Liu Yu also sent troops to contain the soldiers and horses in Liaodong, and Zhang Yu has always remembered this account, but he has not had time to settle it yet.

After the battle with Wu Huan, Zhang Yu was very weak and had no strength to ask for accounts.

After the Xiongnu invaded Youzhou, it was not suitable to find trouble with Liu Yu at this time.

But now that Zhang Yu is busy, he must pay it back.

At this time, Liu Yu had a very difficult time, on the one hand, the Hun invasion, a mess.

As soon as the Huns left, Gongsun Zhan took the opportunity to attack him and kept attacking him.

Liu Yu has a hand in the economy, but he is not good at all militarily, and his territory and status are larger than Gongsun Zhan, but he has been pressed and beaten by Gongsun Zhan.

At this time, Liu Yu was in a hurry, and it was Zhang Yu's revenge before liquidation.

Zhang Yu won't talk to Liu Yu about morality.

Liu Yu attacked himself when he was in the most difficult time, and Zhang Yu just returned the favor with his own way.

Therefore, Zhang Yu took the opportunity to make trouble and directly sent 20,000 soldiers and horses to wander around Liu Yu's territory.

It's just wandering, Zhang Yu doesn't want to start a war with Liu Yu yet.

There is no benefit in starting a war, your own territory has not been digested, and it is useless to fight for other territories, it is better to take the opportunity to extort a large sum.