The Liaojin were assimilated by the Central Plains culture in the wars and peace with the Song Dynasty, and after the Mongols conquered them, they used its aristocratic bureaucrats, which were the first to expose the Mongol nobles to Han culture, among which Yelu Chucai was the most representative.

Yelu Chucai is a descendant of the Khitan royal family and the eighth grandson of Yelu Tuyu, the king of Dongdan in the Liao Dynasty. Yelu Tuyu was one of the first people in the Khitan royal family to accept Han culture, and he governed Dongdan and adopted Han law. He admired the Central Plains culture very much, had a deep foundation in Sinology, and when the Khitan nobles were in turmoil, he fled to the Central Plains to spend the rest of his life. His descendants lived in the Central Plains for a while before returning to the Liao Kingdom and becoming nobles of the Jin Dynasty.

The influence of Sinology has continued in this family, and since Yelu Chucai's grandfather, the family has been a high-ranking official and nobleman of the Jin Dynasty for generations, and has often lived in Yanjing. At that time, Yanjing was the economic and cultural center of the north, and there was a profound foundation of Han culture, which made the Yelu family influenced by Han culture for generations, forming a family style of reading and knowing etiquette. Yelu Chucai was influenced by Confucianism from an early age, and his ideal was to govern the world according to Confucian doctrines.

Yelu Chucai also studied under the master of Caodong Sect Xingxiu, and was influenced by Buddhism, and all his life was based on the Buddha in thought, and followed the Confucian way of helping the world and reassuring the people in action. This makes his thinking another characteristic, although he admires Han culture, he does not have the narrow national sentiments and prejudices of Han scholars. In his opinion, there is no distinction between Huayi and Huayi's defense, and his ideal is that Huayi is unified and shares peace.

In order to maintain the Han culture and make the Mongolian upper class accept the Han culture, Yelu Chucai used the pragmatism of the Mongolian aristocracy, called the rule of customs, mainly from the protection and appointment of Confucian talents, and the dissemination of Confucian etiquette.

After the Mongols conquered the Central Plains, a question arose: How to govern this culturally advanced region? Yelu Chucai said: "Although you can win the world immediately, you can't rule the world right away. ”

He knew that in order to rule the Central Plains, he had to use the system of the Central Plains, and it was the Han Confucian scholars who were familiar with the way of Han law rule. So when he was in power, he vigorously protected the Han Confucian scholars and introduced them to the official career, Yelu Chucai set up ten roads in the Central Plains jurisdiction, and each road appointed the chief and deputy tax envoys, all of whom were Confucian scholars.

During the Mongol destruction of Jin and the conquest of the Southern Song Dynasty, many celebrities such as Yuan Haowen, Zhao Fu, Dou Mo, Wang Pan and others were protected and used, which had a great impact on the prosperity of the northern style of study. With the fall of the Jin Dynasty and the expansion of the ruling territory, the country needed a large number of talents to govern the country.

Yelu Chucai said: "Those who make utensils must use good work, and those who keep the state must use Confucian ministers." Ogedai listened to him.

He selected many talents, such as Yang Huan, Zhang Wenqian, Zhao Liangbi, Dong Wenyong and others, who were later famous ministers in the Kublai Khan era and made great contributions to the completion of the Sinicization of Mongolia. The examination enabled a large number of Confucian scholars to obtain higher status and preferential treatment in class service, and played an important role in the fields of culture, education, politics, and economics.

The Mongols were a nomadic people, in a slave society, and all institutions and forms of social organization were based on tribal chieftains. This kind of system was undoubtedly extremely backward for the Han nationality areas that ruled the advanced areas, and it could not meet the social requirements of the time. Yelu Chucai saw this, so he began to reform in all aspects.

The Mongol kings and ministers held the Kuritai Assembly in the Qulvlianhe Qudiao Alan area, and discussed the succession issue for forty days at the meeting, until the forty-first day, when the result was reached, and Ögedei ascended the throne.

At the time of Ögedei's accession to the throne, Yelu Chucai formulated a canonical ceremony in accordance with the tradition of the Central Plains Dynasty, which required the royal family elders to worship the Great Khan in the banlie, which was not very consistent with the traditional Mongolian customs.

In the past, there were no formal courtiers in Mongolia, and the Kuritai Assembly was actually a council of tribal confederations. The Great Khan was equivalent to the head of the tribal confederation, and although he had supreme military power, he still regarded the tribal chiefs as brothers in etiquette, and there was no strict distinction between the rulers and the ministers. The implementation of the Worship Khan Rite was the inheritance of the Central Plains ritual system, which showed the supremacy and unsurpassed power of the Great Khan, which was preserved even after the fall of the Yuan Dynasty and the retreat of the Mongols to the steppe.

One of the biggest goals of Yelu Chucai's administrative reform was to weaken local power and strengthen centralized power. Yelu Chucai was appointed as the Zhongshu Order, and was given full authority to establish the Zhongshu Province, and the Mongol Empire began to have a central administrative body. Although the Zhongshu Province is only a team such as the secretariat, it actually has a lot of power because it is related to the issuance of documents and the handling of important affairs such as documents.

In the process of the rise of the Mongols and the conquest of the Jin State, a large number of Jin officials and landlord armed leaders were attached to the Mongols, mainly Han Chinese, but also Khitans and Jurchens. They gradually became the new magnates of the Mongols, forming local forces on the authoritarian side. During the Mongol period, the feudal system was also implemented, and the rulers divided some northern prefectures and counties to the kings, meritorious officials, and horses as a cast, and the official positions and territories of these powerful people were hereditary.

In his jurisdiction, they combined military, civilian, and financial powers, and were both military governors and administrators, and they could appoint their own subordinates, appoint subordinate officials, set their own taxes, and collect them, which was very similar to the feudal towns of the Tang Dynasty. Although their contributions and armies were the main sources of the Mongol finances and military, their dominance was fundamentally detrimental to Mongol rule.

The Han dynasty had a group of dependent populations and a large number of slaves, and this phenomenon of strengthening the dependency relationship of life was actually a kind of regression, which was a tribal chieftain and slavery-style management, and also a special combination of the early Mongolian feudal system and the feudal production relations in the Central Plains.

Mongolia's legal system is extremely naïve, and with the expansion of Mongolia's ruling area, problems such as social security and the bureaucratic system have become increasingly serious. Genghis Khan's Zaza, which resembles the rules within a tribal alliance, is simply not able to adapt to the complex social situation. At that time, the governor of the prefecture and county was greedy and rampant, the rich arbitrarily annexed land, and the phenomenon of ruffians and hooligans killing people and extorting goods was very serious.

In view of the social reality, Yelu Chucai put forward a provisional law based on a number of legal principles of the Central Plains, and made specific provisions on the problems of local officials doing errands without authorization, merchants embezzling official goods, Mongolian nobles not paying taxes, embezzling official goods, and death sentences, which made the social situation at that time somewhat better.

In the territory of the Mongols, the economic components are diverse, there is an agrarian economy mainly in the Central Plains, a commercial economy throughout the country, mainly managed by the Semu people, the royal family and princely ministers are willing to invest, and the nomadic economy is mainly in the Mongolian plateau and steppe areas, the Mongolian aristocracy does not value the agricultural economy, but is enthusiastic about the huge profits brought to them by overseas trade.

The Mongol cavalry was invincible, but its victorious rule fully exposed its backwardness. As a result, there was a conflict between Huhua and Sinicization in the Central Plains, and in this conflict, the danger of historical regression has been revealed. With his wisdom and ability, Yelu Chucai guided the rulers to see the superiority of the Han civilization, established the etiquette and taxation system that Mongolia itself did not have, gradually disappeared the backward feudal system and the management system of tribal alliances, and enabled the development and growth of Mongolia's naïve legal system, which contributed greatly to the transition from Mongolia to the Yuan Dynasty.

Unfortunately, during his lifetime, many of his suggestions and ideas were not vigorously implemented and undermined, and were obstructed and sabotaged by the aristocracy and the merchants. This is inseparable from the social situation and national character at that time, the rulers had the intention of accumulating wealth and military force, but had no intention of appeasing the people, and the people had no intention of producing and were tired of running for their lives in the war and chaos.

However, Yelu Chucai's actions played a role in connecting the previous and the next, and in the later great cause of Kublai Khan's establishment of the dynasty and the further sinicization of Mongolia, he basically followed the path he walked and carried it forward. Even after the fall of the Yuan Dynasty, the nobles who retreated to the Mongolian steppes unconsciously followed certain principles of the Han system when establishing a new state. Although the sinicization of Mongolia is very shallow, it is difficult for Kublai Khan to make entrepreneurial exploits without Yelu Chucai, and it is difficult to repay Yelu Chucai's ambition without Kublai Khan.

The destruction of the Jin Dynasty was Genghis Khan's established policy, and after Ogedai ascended the throne, he launched the War to Destroy the Jin, when the Jin had already gotten rid of the situation of being attacked on three sides and could concentrate his forces to compete with the Mongol army. Jin Aizong reorganized the Jin army and formed an elite army of more than 100,000 people, divided into 15 lieutenants, as a strategic mobile force directly subordinate to the Privy Council.

The general Wanyan Heda, who had repeatedly made military exploits, was selected as the deputy envoy of the Pingzhang government affairs and the privy councillor of power, and the important minister who supported the succession of Aizong was promoted to the position of the privy envoy of the power, and jointly served as the commander of this mobile force. In addition, there are more than 200,000 troops, and the total number of troops is still more than 400,000, so it is not easy for the Mongols to destroy Jin.

The Mongol army was led by Duohulu to besiege Qingyang, Shaanxi, and in order to delay the army, the Jin State not only sent sheep wine to treat the Mongol army, but also sent envoys to the Mongol Khan's court to ease relations between the two sides, which was refused. In the first month of the following year, the Jin army defeated the Mongol army at Dachangyuan and relieved the siege of Qingyang. This was the biggest victory of the Jin army since the Mengjin War.

Wokotai worshiped the sky for nine days and decided to go on a personal expedition. The emperor's brother Tuo Lei, the emperor's nephew Meng Ge led the army to follow, and the kings Alecchi, Kouwen Buhua, etc., each led the men and horses of their headquarters to attack the Jin army in three ways. In August, Shi Tianze, a famous Han general of the Eastern Route Army, entered the siege of the Jin Army Wuxian in the old Weizhou, and the Western Route Army was led by Tuo Lei, and went south to join the Mongolian army in the Qingyang area, and besieged Fengxiang in the spring.

Wo Kotai personally led the Central Route Army across the Yellow River, occupied Tongzhou, Huazhou, and parts of southeastern Jingzhao, and pinned down the more than 100,000 mobile troops led by Heda and Pua, who were stationed in Ruxiang and Mianchi. In November, Subutai was sent to attack Tongguan and Languan, and the commander-in-chief of Jintongguan Nahebuyu, and the loyal and filial piety army Wanyan Yi led the army to resist the battle, and Subutai was defeated, which was the so-called victory of the Jin army back to the valley.

In the first month of the following year, Subutai broke through the small pass in the south of Tongguan, and Lushi, Zhuyang and other places were destroyed. In April of that year, the two provinces of Heda and Pua decided to abandon Jingzhao, and ordered Jingzhao to move the residents to Henan and surrender Tongguan. From then on, the west of Tongguan was no longer the land of the Jin Kingdom, and the Mongol army occupied a strategic base to march to Kaifeng, the capital of the Jin Dynasty.

Wokotai took refuge in the summer at the Ninety-Nine Springs of Guanshan, convened a meeting of the kings and generals to discuss the strategy of destroying gold, and made a strategic deployment of three ways to destroy gold. The Great Khan of Wogetai personally led the Central Route Army to cross the Yellow River from the southwest of Shanxi, captured Hezhong Prefecture, entered Luoyang, and pointed directly at Kaifeng; the Left Route Army attacked Jinan, Shandong; and the Right Route Army, led by Tuo Lei, made a detour through the Song Realm, sent troops to Tang and Deng, and smashed the back of Bianjing. The three armies agreed to meet Kaifeng in the spring of the second year and destroy the Jin Dynasty.

In July, when Tuo Lei went south from Fengxiang, he first sent an envoy to the Southern Song Dynasty and Sichuan in the hope of making a false path and making an appointment to destroy Jin, but the envoy was killed by the Southern Song Dynasty guards as soon as he arrived in Qingyeyuan, Shaanxi. Tuo Lei was furious, so he led the army into Dasanguan and entered the Song Realm after breaking the Baoji. The southward swept the Da'an Army, Lizhou, Daizhou and other places, and broke through the military retreat, and captured Yangzhou through Huayang and other places.

The vanguard general pressed Zhu'er to Sichuan to make Gui Ruyuan pretend to be Song Dao, and Gui Ruyuan was forced to send a guide to lead the Mongolian army through Fengguan and Jinzhou to capture Fangzhou. The Mongol army marched north, broke the Jin soldiers at Wudang Mountain, and reached Junzhou on the south bank of the Han River. Crossing the Han River from Junzhou, entering the Tang and Deng regions of the Jin Dynasty, and completing the false road to the Song Dynasty.

Under the personal leadership of Wo Kotai, the Central Route Army conquered Hezhong Fu in December of that year, and the Wo Kotai Army crossed the Yellow River from Baipo, Heqing County. At this time, the messenger who dragged the mine sent the news that the right army had crossed the Han River, and Wokotai immediately sent more than 10,000 cavalry led by Zhuwangkou Wen Buhua and others to respond.