Compared with the countries conquered before the Tang Dynasty, Tibet was not the most powerful in national strength, and the population and financial resources of Goguryeo, Unu, Eastern Turks, Western Turks, and Xue Yantuo surpassed those of Tibet.

However, Tibet was the most difficult to conquer.

Tibet has three major characteristics:

First, geographical advantages.

Tubo is located on a plateau with poor climatic conditions, and it is difficult for the army in the Central Plains to adapt. The high mountains are steep, the rivers are crisscrossed, and the road traffic conditions are even worse, so it is very difficult for us for the Tang Army, which relies on logistical support.

Second, the political system.

Like the Tang Dynasty, Tibet practiced a centralized system, and Songtsen Gampo had the strong influence of this person, and the country as a whole had a high degree of unity and support for the war.

Third, religious influence.

Tibet believes in Tibetan Buddhism, and the Tibetan people are under its control, and have the spirit of dedication to religion, and the people are not afraid of death and have a strong will to fight.

Tibet was still a slave state, and slaves were ideologically subordinate.

In the battle, the Tang army encountered the Tubo people, who fought bravely, and almost none surrendered.

Therefore, every time the Tang army fought, no matter how many enemies there were, it encountered a bitter battle. The losses of the Don army were serious.

Under these circumstances, it would be difficult for the Tang army to achieve control over Tibet even if it captured the city of Lhasa and even eliminated the ruling group in Tibet.

After careful consideration, Li Su decided to adopt a new policy of division and disintegration.

The first step was to suspend the offensive militarily and consolidate the existing occupied areas while maintaining strong military pressure on Tibet.

Concentrate heavy forces, repeatedly clear the occupied areas, and completely destroy all armed resistance.

The second step is to establish and improve the organs of political power.

A large number of officials were transferred from the interior and sent to Tibet in the form of official ranks, and government agencies at all levels were established, and corresponding armed forces were used to strengthen the management of the occupied areas.

The third step is to carry out land reform in the occupied areas in accordance with the standards of the land equalization system.

The political privileges of the slave-owning part were retained, and all slaves were emancipated, which not only won the support of the majority of slaves and commoners, but also left a way out for the slave-owners.

These were concrete measures to solve the Tibetan problem, and in order to improve the sense of identity of the Tang people and dismantle the will to resist the newly conquered areas in the future, Li Su put forward the theory of a third-class national.

Since October 1, 642, all the original citizens of the Tang Dynasty have become first-class nationals.

In the newly occupied areas in the future, the newly joined Datang nationals are second-class nationals.

In the newly conquered areas, the captured soldiers and others who participated in the rebellion against the rule of the Tang Dynasty were third-class nationals.

Different levels of citizens enjoy different treatments.

Organized by the government, an evaluation is conducted every two years, and those who abide by the laws and regulations of the state, pay taxes on time, and have no disciplinary violations within two years can be promoted to the national rank.

Those who violate the laws of the country and fail to pass the evaluation will have their national rank reduced.

Those who have made special contributions to the country, such as those who have military merits, or in other aspects, who have contributed to the imperial court, can be promoted in advance.

Violation of national laws, even if not punished by law, can be compared to the rank of citizens as appropriate.

When this hierarchy was promulgated, it immediately caused a strong reaction in society.

Whether it is the Goguryeo, Unu, Silla and Baekje people, they are very fortunate that they have all become first-class nationals of the Tang Dynasty, which has strengthened their sense of identity with the Tang Dynasty. To a great extent, national contradictions have been reduced.

This measure has also raised the pride of the entire Datang people. The patriotic consciousness of the entire Tang Dynasty has been greatly improved.

For the Tubo people, in order to stand up to the national level, they abide by the law and discipline, and conditionally strive for meritorious service awards, which also enhances their sense of identity with the Tang Dynasty. It greatly reduces the difficulty of government management.

In the areas occupied by the Tang army, there were basically no large-scale rebellions among the Tibetans.

This policy also played a very good role in disintegrating the enemy's army in future wars.

In the war of 642, Songtsen Gampo lost the territory east of the Nu River and north of the Kunlun Mountains, accounting for more than 1/4 of the entire territory of Tibet.

When he saw the policy adopted by the Tang Army in the newly occupied areas, he felt a deep sense of helplessness, and he had basically lost his influence in those areas.

Through the deliberate propaganda of the Tang Dynasty, the policies adopted by the Tang army in the newly occupied areas also had a great impact on the people in the areas controlled by Tibet.

Becoming a citizen of the Tang Dynasty has become the happy life they yearn for for the commoners and slaves of Tibet. The influence of the Tibetan authorities on this part of the population was greatly weakened.

On the east bank of the Nu River, Hou Junji's headquarters.

"Dashuai, in the past half month, there have been a total of 326 Tubo people who have escaped from the Nu River, which is a lot less than the first half of the month. The Tibetans have strengthened their defenses on the other side of the Nu River, and I have seen them kill many Tibetans who tried to smuggle their migrants. The chief of staff of the Eastern Route Army Command said.

Hou Junji said with a smile: "If you kill well, the more they kill, the more they will lose the hearts of the people, and if you continue like this, Songtsen Gampo himself will collapse." ”

The Tang army carried out propaganda against the Tubo people, and the Tang Dynasty gave preferential treatment to all the Tubo people who fled to the Tang Dynasty, and directly designated them as second-class nationals, and distributed them with grain, real estate, and land. It attracted a large number of Tibetan people to come to the Tang Dynasty.

The chief of staff said: "The emperor's plan is really poisonous enough, the population of Tibet is not large, and if it continues like this, Tibet will collapse sooner or later." ”

Hou Junji said with a smile: "When the emperor was 14 years old, when he was still King Liang, I recognized him.

At that time, he was not a prince, and he was not a concubine, and no one was optimistic about him at all, but I felt that he would be able to succeed in the future and marry my only beloved daughter to him.

As it turned out, I made the right decision. ”

The chief of staff said: "That is, Grandpa Guo's vision has always been unique, not only for his humble position, but also for everyone's admiration. ”

Songtsen Gampo tried to crack the moves of the Tang Dynasty, and once thought about implementing land reform and improving the treatment of civilians and slaves in the existing control areas to win the hearts of the people.

However, the basis of the Tibetan regime was the slave-owning class, and it was impossible to carry out land reform and emancipate slaves. If Songtsen Gampo did this, his regime would fall immediately.

What he didn't know was that he would face an even greater catastrophe for Tibet.

After Xue Rengui drove away the Arabs, he received an order from the general Li Jing, and after he arranged the affairs of Persia, he led 150,000 Tang troops and embarked on the road of Gao Xianzhi's expedition.

Northern Tibetan Plateau.

Gao Xianzhi's troops continued to confront the army of the Ring Sun Kingdom, during which he carefully surveyed the terrain of the entire war zone and was ready to go to war with the Ring Sun Kingdom at any time.