In Pengcheng, the capital of the Song Dynasty, Dai Yan was extremely happy when he saw Su Li, the envoy who returned to China.

Su Li's envoy to the State of Chu this time and signed an alliance with the State of Chu brought the benefits to the State of Song were too huge. Such a huge benefit made him a little unbelievable to this day.

The peace between the Song State and the Chu State was to get the Song State out of the war with the Chu State. The Song State's raid on the Chu State this time, although it was also after many years of preparation by the Song State, was able to succeed in one fell swoop. However, in order to achieve such results, the Song State also paid a huge price. At present, although there is an incomparably prosperous war economy in the entire Song State because of the war, the hundreds of thousands of troops of the Song State are either far away in the south, or they are preparing for war, which makes it impossible for a large number of adult men in the Song State to devote themselves to national construction, which greatly restrains the current strength of the Song State.

The end of the war will certainly make the prosperous war economy stagnate, but Dai Yan believes that there will be no shortage of war in the Warring States today! Especially after the state of Chu received a "land purchase" fee provided by the state of Song, the king of Chu had infinite confidence in the war with the states of Qin, Wei and Han!

In this way, the military industry of the Song State itself as a result of the war will not fall into decline because of the sudden end of the war. A large number of labor forces of the Song State could be freed up from the war, which allowed the Song State to absorb the fruits of the war relatively quickly.

Now that the Song State and the Chu State have reached an armistice agreement, the Song State has obtained a vast territory from the southern part of the Song State to the Yuedi Huiji! This vast territory is almost equivalent to the entire range of Yangzhou in today's Kyushu.

Among the nine states in the world, Yangzhou is definitely a large state that can rank among the top in terms of territorial area. Before this war, not counting the previously expanded land of the East China Sea, the territory of the Song State itself was only a small country with a radius of 500 miles. However, Yangzhou alone is almost ten times the size of the Song Kingdom before!

Of course, the strength of a country's national strength is never determined solely by the size of its territory, but mainly by how many troops the country can mobilize and how long these forces can support the war.

That is to say, the specific support of national strength depends on the size of the population and the strength to create wealth to support the war, and in general, the strength of the national strength is related to the degree of local development. With the current situation, the degree of development of the Jiangnan and Jiangbei regions is naturally far inferior to that of the Song Dynasty itself. Today, although the Song Kingdom itself is only a small country with a radius of 500 miles, its population exceeds 3 million, and it is considered a densely populated country among the countries under heaven.

Although the territory of the land south of the Yangtze River and Jiangbei is much larger than that of the Song Dynasty itself, its registered population is not as good as that of the Song Dynasty itself. The newly conquered territory is a vast and sparsely populated land, although the territory has expanded tenfold, it does not mean that the strength of the Song State has expanded tenfold.

However, the expansion of the territory of the Song State still had great benefits. If a country wants to become a great power, it must first have a vast territory. A country with a vast territory can withstand more challenges and have a higher tolerance for error, which is an unbreakable truth in both ancient and modern times.

In the Spring and Autumn Period, Zheng Guo, the first hegemonic power, soon fell into weakness, although there are reasons why Zheng Guo is located in the land of four wars, but the biggest problem is that Zheng Guo's territory is small and the fault tolerance rate is not high. A slight internal strife, coupled with the rise of a neighboring power, quickly weakened.

Such an example is applicable even in the later modern era of industrialization. A typical example is a small country like the Netherlands and a big country like Russia.

In the 17th century, the Netherlands, known as the coachmen of the seas, built an incomparably powerful maritime empire. At that time, even the Russian Tsar traveled from his home country to the Netherlands to study. However, its small territory is its biggest weakness. When it was challenged by the rising British, lost its maritime supremacy, and was attacked by France by land, it quickly weakened from its position as a great power.

On the other hand, Russia, whether it is the feudal era, or the era of its gradual industrialization, entered the Soviet era, and then entered the Russian era, although it has experienced many wars, and sometimes even wars that can determine the survival of its country, it is still a great power with great influence in the world. What is it based on? It's nothing more than a vast territory that allows it to raise as many citizens as possible and has greater tolerance for fault.

Today, the expansion of the territory of the Song State not only represents the growth of the Song State's heritage and can have greater fault tolerance, but also represents the infinite bright prospects for the future of the Song State. Although Yangzhou, where Jiangnan and Jiangbei are located today, belongs to the "lower ninth class" in the eyes of the world, the most barren territory, but in the view of Dai Yan, who knows the future, the development prospects of this land are far as the richest places today.

Nowadays, in the Warring States period, even if the Song State has a slight shadow of capitalism, the whole world is still dominated by agriculture. The richest place in the world is the place where the land is most fertile and agriculture is the most developed. And these places, in fact, are nothing more than relying on the Yellow River, Huai River, Jishui, Weishui and other major rivers.

As the origin of Chinese civilization and the mother river of the Chinese people, the Yellow River Basin is the most well-developed place in the whole world. Even in today's times, the river itself is not as muddy as it was in later generations. At this time, its name was still called the Great River! And the Qin, Wei, Korea, and Zhao countries through which its main rivers flow, are the richest places in the world!

The Huai River and Jishui, because they are located not far from the Yellow River, are also relatively well-developed places in the world. The area through which the Huai River flows is divided between the states of Chu, Wei, Korea and the Song kingdoms. Speaking of which, the war between Chu, Wei and Han is so fierce now that it is because they all need to be in the same area and need to constantly strive for their own interests.

As for Jishui, it was mainly divided between the Wei, Song, and Qi states. Speaking of which, the Song State was able to raise a population second only to the big countries in the world as a small country, and the rich place occupied by the Song State was definitely indispensable!

As for the other rivers in the world, such as the Weishui of Qin, the Han of Chu, and the Zishui near Linzi of Qi, although most of them are rich places, they are only the water of one place after all, and their influence is not very large.

And Dai Yan, who is familiar with history, knows very well that although the north is now well-developed and far more prosperous than the south, in Dai Yan's view, the development of the north is far inferior to that of the south. This difference in heritage has nothing to do with population, customs, etc., and is entirely caused by the differences between the two rivers themselves, the Yellow River and the Yangtze River.

In an agrarian civilization, water is the biggest problem. During the Warring States period, humans were able to modify some of the natural environment, such as cultivating ditches to promote agriculture, but this did not fundamentally change the biggest difference between the two rivers.

Compared to the Yellow River, the Yangtze River has a larger water flow, which can provide more abundant water sources to the south. The Yangtze River has such an abundant water source, and what is even more commendable is that it has huge and vast lakes such as Dongting Lake, Poyang Lake and Taihu Lake, which can be used as a reservoir for the Yangtze River, which can largely avoid large-scale flooding in the south.

Although the northern part of the country is vast and well-developed, there are no lakes with deep heritage in the north centered on the Yellow River, except for Fengzawa and Onozawa. In today's era, when there are not many disasters in the world, Bonizawa and Onozawa can also be used as reservoirs in the north to slightly absorb the floods encountered in the north.

However, in the future, when the war between the heavens and the earth becomes more and more intense, all countries will do everything in order to win! Among them, the most prominent tactic is to attack the city with water. In Dai Yan's memory, the Wei capital Liang, as well as the capital of Chu, Yancheng, were all buried under the Qin army's water attack! In this kind of war to destroy the country and destroy the city, it is really too easy to destroy the environment in the north.

And such destruction, for the North, is almost permanent! Dai Yan remembers very well that in the future, the Yellow River in the north will gradually become a "hanging river" due to the gradual destruction of the environment. Even after the Song Dynasty, once the Yellow River burst, it was able to directly divert the river, leaving poison for hundreds of years!

As for the South, there are no more problems faced by the North. In the Yangtze River basin in the south, because there are deep lakes such as Dongting Lake, Poyang Lake and Taihu Lake as reservoirs, there is almost no need to worry about flooding! Even in times of war, when the southern city is attacked by water, it is impossible to directly change the entire environment as in the north!

To put it mildly, as long as the Song State can manage the land of Yangzhou that it occupies today and guard against the attacks of other countries, this place can completely achieve a thousand-year-old foundation!

Of course, things in the world are never so simple. First of all, let's talk about the development of the south, which is by no means something that can be accomplished in a short period of time.

In later China, there was a famous Qinling-Huai River line. On both sides of this line, there are obvious differences in natural conditions, agricultural production methods, geographical features and people's living customs. As a classic summary of geography, Dai Yan naturally will not forget this important fact.

The current Song State can be said to be completely north of the Huai River, and in this land, the crops that can grow are millet, and after Dai Yan took charge of the Song Kingdom, most of them have become wheat. However, neither millet nor wheat is actually suitable for growing in the south.

The south is rainy and the air is relatively humid, which is suitable for the growth of rice. When Dai Yan had just crossed over to the Warring States Period, the crops planted by Chu State, the most important country in the south, were called rice, and such a kind of rice was actually completely different from the rice that Dai Yan saw in later generations.

Although the Chu people grow rice, in Dai Yan's view, this crop can only roughly be equivalent to the millet of later generations, and it cannot be compared with the real rice of later generations! Not only is it unpalatable, but its yield is also extremely low, and it is completely incomparable to the millet and millet grown in the northern countries.

As for the south, Dai Yan has coveted it for a long time, so he will naturally make preparations for the development of the south. When he sent his peasant disciples to travel around, he made them pay special attention to the unique crops that the south possessed, especially the wild rice!

After so many years, after the collection of peasant disciples who traveled abroad, plus the cultivation of the Song State Seed Department, Dai Yan was finally able to get the rice seeds he wanted.