Tang Dynasty Contradiction

The first one is the contradiction between farmers and landlord, also a contradiction between farmers and new dynasty.
The fierce confrontation between farmers and old dynasty, landlord tends to ease at the start of a new dynasty. If the new dynasty rulers adopted a series of policies to ease the conflict, such as minimal tax burden, straighten officialdom, austerity, etc., it can resume production and economic prosperity. Examples include the prosperity during the reign of Wen and Jing Emperors of the Western Han Dynasty, Golden Years of Zhenguan, peak of Tang prosperity during Kaiyuan, and booming and golden age of the Qing dynasty. However, if the policy of the new dynasty does not allow people to rest, but extorting taxes and levies, stricting

During the period of dynasty replacement, the previously suppressed northern nomads suddenly rose up, southward invasive the new dynasty, the new dynasty should take different strategies depending on the conditions.
For example, the Western Han Dynasty, national strength is still relatively weak, the ruling is not solid, so to deal with the northern nomadic the emperor chose to compromise and made a marriage alliance. Until seventy years later, national strength was stronger, Emperor Hanwu made a massive attack on the northern nomads with a decisive victory.
Emperor Taizong of Tang dynasty, first chose to compromise to the Eastern Tujue’s attack, after preparing for three years he attacked and expelled Eastern Tujue.
Faced with these contradictions, if refuse to take the historical experience and taking inappropriate strategies, it will often shorten the life of the dynasty.
To prevent farmers revolt, the Song dynasty strengthened autocratic centralization, maintained a large number of soldiers and officers, arose the problem of "redundant soldiers, officers and military expenditure", resulting in "poor and weak" situation.

Response to the

A new dynasty established after a peasant uprising usually learned from peasant uprising, and the mistakes from the old dynasty. Some people in the Western Han Dynasty always pay attention not to track Qin dynasty did. Emperor Taizong of Tang dynasty kept warning himself about the decline of Sui dynasty. New dynasty’s success is related to how the new dynasty rulers look at the lessons of history, and taking the right measures.

Ancient China is not only an agricultural society, but also a class society. Dynasties rulers are exploiters, they pursue their own interests. They could accept the lesson from peasant war, accept the experience of a dynasty’s decline from previous one. But usually when they are powerful enough, they no longer have self-control. Autocratic centralized state bureaucracy at all levels and officials at all levels is a very important part to prevent the decline happens again. So the rulers always pay great attention on management problems. Often after dynasty raised rulers very careful straighten officialdom, like the Western Han Dynasty, Tang Dynasty, and the Ming Dynasty. The reason why a dynasty decline, a big part of that is the political