The Khitan state is also what we often call the Liao state, but it is a fierce enemy of the Northern Song Dynasty, which almost makes the Northern Song Dynasty to the point of fear and fear. The Northern Song Dynasty was founded in 960, and it was Zhao Kuangyin of the Later Zhou Dynasty who carried out a Chen Qiaoyi mutiny, and added his yellow robe to his body and replaced it. However, the Khitan state was established earlier than the Northern Song Dynasty, even earlier than the Later Zhou Dynasty when Zhao Kuangyin served, and the Khitan was founded in 907 by the Khitan Yelü Abaoji, but during the second emperor Liao Taizong, the founding name was Daliao.
After the establishment of the Northern Song Dynasty, there were also Forces of Later Shu, Southern Han, Southern Tang, Wuyue, and Northern Han at the same time. Therefore, Zhao Kuangyin's goal is to dominate the world. Zhao Kuangyin adopted a strategy of first going south and then north, and it was not until Zhao Guangyi's reign, that is, in 979, that he eliminated the Northern Han Dynasty and formally unified the whole country.
So why didn't the Khitan attack the Northern Song Dynasty in the past twenty years? In fact, the reason is very simple, the Khitan at that time had changed its name to Daliao, and the political situation in the Liao state was turbulent. Moreover, the liao state's rule in the Central Plains was unstable, forcing the then emperor Liao Muzong to stop the policy of southern expeditions to the Central Plains that Liao Taizong and Liao Shizong had always implemented.
It would be wrong to say that the Liao state had no ambitions. Since the establishment of the Khitans, the southward central plains have been their goal. The second emperor of the Liao state, Emperor Taizong of Liao, also inherited the cause of his father, Liao Taizu Yelü Abaoji, and used troops to the south to dominate the Central Plains. It was also he who assisted Shi Jingyao in destroying the Later Tang, obtaining the Sixteen Prefectures of Youyun, and eventually eliminating Shi Jingyao's Later Jin, occupying most of the Territory of the Central Plains.
After Emperor Taizong of Liao's death, his nephew succeeded to the throne, but during his reign, the political situation was unstable and internal rebellions continued, and he eventually died in a coup d'état. Of course, the one who succeeded him, that is, Liao Muzong Yelü Jing, did not end well and also died in the coup.
It was also during the reign of Emperor Muzong of Liao that the Northern Song Dynasty was established. But at this time, we can find that Daliao is in an infighting and cannot extricate itself.
At the same time, due to the perennial wars of the Liao State, the national strength was damaged, and the focus had to be placed on the country. Facing the south, it can only strengthen the defense.
Although Emperor Jingzong of Liao was diligent in government affairs and reused Han Chen, he caused a burst of clarity in Daliao. However, in the early period of his reign, foreign policy still adopted the policy of not taking the initiative to conquer the Central Plains in the south and only aiding the Northern Han Dynasty.
And this also gave the Northern Song The opportunity, of course, the Northern Song strategy itself is to first south and then north, so for a period of time, the Northern Song Did not take the initiative to provoke the Liao.
During this time, the Liao Dynasty and the Northern Song Dynasty hired history to return to each other and exchanged congratulations on festivals. The relationship cannot be said to be good, but it remains normal. But after Zhao Guangyi came to power, it was different, Zhao Guangyi set his sights on the Northern Han, and he also personally conquered the Northern Han, and the Liao State could only send troops to support, but was defeated. After the fall of the Northern Han Dynasty, Zhao Guangyi continued to continue the Northern Expedition to the Great Liao, but the result ended in failure, and even Zhao Guangyi almost did not return.
Subsequently, Emperor Shengzong of Liao succeeded him, and Xiao Yu became the empress dowager's regent. It was through the efforts of these two men that the Great Liao entered its peak and actually led a large army to invade the Northern Song Dynasty, which also began another period of history between the Song and Liao.