Emperor Yang Di Yang Guang is notorious 14 years.

Speaking of Yang Di, he is basically a tragic figure, rainbow mang. The Eastern Han Dynasty tried to discredit Wang Mang for its own rule. This is also the virtue of the Tang Dynasty. Hei Di and Yang Di in the Tang Dynasty changed their ways, and they have this virtue since ancient times.

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In fact, after careful analysis of Yang Di's policies, these policies were still in use in the Tang Dynasty. Yang Di failed because he was too eager for quick success and didn't take it step by step. For example, Yang Di wants to be Emperor Wen and Emperor Wu of Han Dynasty. As a result, it developed too fast, leading to the collapse of the empire.

First of all, Yang Di opened the Grand Canal not only for so-called entertainment.

In the history of the Tang Dynasty, it has always been said that Emperor Yang Di dug the Grand Canal for fun. In fact, this is to discredit the emperor. From an objective point of view, Jiangnan tourism is indeed one of the reasons for digging the Grand Canal, but it is only the least important one. As the ruler of the unified dynasty, Yang Di's main task in digging the Grand Canal was to stabilize the situation in the south. Although in 589, Sui Jun was destroyed by the Southern Chen Dynasty. But the southern forces didn't really give in. They are always waiting for the opportunity to act. Before the Grand Canal was dug, there were two large-scale rebellions in Jiangnan area. Although they were successfully suppressed by Sui Jun, Sui Jun also exposed the problem of untimely response. Yang Di once and for all mobilized a large number of people to dig the Grand Canal. Facts have proved that Emperor Yang Di's consideration is very correct. Among the heroes in the late Sui Dynasty, those Jiangnan nobles really took the opportunity to alienate each other.

In addition to stabilizing the situation in the south, there is also the food problem. With the economic recovery in the north, the population of Chang 'an and Luoyang is increasing, and relying on the grain produced in the north can no longer support a large number of people who are not engaged in agricultural labor. This is why Yang Di moved the capital from Chang 'an to Luoyang. Grain from the south can be transported directly to Luoyang through the Grand Canal. The populations of Luoyang and Chang 'an are over one million. After Yang Di moved to the capital, it can bring nearly 200,000 people, which can greatly reduce the pressure in Guanzhong. Another point is to break the monopoly of the nobility. The aristocratic forces in Guanzhong area are intertwined and have a great influence on imperial power. After moving the capital to Luoyang, these aristocratic forces can be uprooted. After the establishment of the Tang Dynasty, this policy was continued. During the period of Emperor Taizong, the aristocratic forces in Guanzhong gradually disintegrated.

Two or three expeditions to Koguryo to conquer the nomadic people in the north.

Some people think that Yang Di's attack on Koguryo is his great sin, which is too wrong for him. After him, Li Yuan, Li Shimin and Li Zhi are attacking Koguryo, which belongs to the local separatist regime in China and should be part of China's reunification war.

The land controlled by Koguryo has always been the territory of China from the Qin Dynasty to the Western Jin Dynasty, and every talented emperor hopes to recover this area. There is nothing wrong with Yang Di attacking Koguryo. The mistake lies in continuous attacks. Due to the weather and terrain, the Sui army failed to attack Koguryo for the first time. Yang Di, a competitive country, has waged two wars in succession. At that time, the foundation of the Sui Dynasty was still very thin and could not stand too much trouble. Three large-scale wars further exhausted the national strength of the Sui Dynasty and accelerated the political turmoil in the Sui Dynasty. Since then, Li Shimin has become smarter. After Koguryo's crusade failed, he left this task to his son instead of sending troops again.

Sui Jun also took the initiative to attack the grassland nationalities in Northeast China, which was regarded as another sin of Yang Di. In fact, Emperor Yang Di did this for a reason. At that time, the national policy of the Sui Dynasty was to attack the west and defend the north, and the Sui Dynasty hoped to open up the Silk Road in an all-round way. However, if the Sui Dynasty paid all its attention to the west, the grassland people in the northeast were likely to constantly harass the border of the Sui Dynasty. Although they could not threaten the rule of the Sui Dynasty.

Therefore, Yang Di took the initiative to attack the people on the northern grasslands, even asking for trouble. Yang Di launched a large-scale conquest of Qidan on the pretext that two businessmen were killed by Qidan soldiers. This is not belligerence, but clearing the way for the west. After the establishment of the Tang Dynasty, this policy continued, and the only difference was what Yang Di wanted to achieve. The Tang Dynasty was completed in three generations.

Third, governing a big country, such as cooking something fresh, can't wait for everything.

Yang Di failed because he was too eager for success. He wants to finish everything by himself. However, he did not consider the people's affordability. At that time, the country had just been unified and was not rich in all aspects. There is nothing wrong with Emperor Yang Di's policies, but these policies are enough to trigger a peasant uprising. At that time, the Sui Dynasty was in danger, and the peasant uprising inspired all unstable factors. Jiangnan Group, Guanzhong Group and those careerists all sprang up, and the situation in Sui Dynasty developed irretrievably. At this time, Yang Di tried to gain a foothold in Jiangnan and then unify the world. But the mutiny in Yu Wenhuaji ruined everything. After Yang Di's death, his cousin Li Yuan began to clean up the mess. After ten years of war, the Tang Dynasty unified the whole country. From the policies of Tang Yuan, Li Shimin and Li Zhi, we can see the shadow of Emperor Yang Di, and there is no urgent need to govern the country. For example, the United States, the world's number one, developed 150 years before it became the world hegemon.