This single-source alliance was an agreement reached between the Northern Song Dynasty and Liao State after years of war. Before that, Liao had been harassing the border areas of Song Dynasty, plundering property, killing people and so on. Let the relationship between Song and Liao gradually tense up, and then Song saw that the situation was wrong and immediately sent troops to crusade against Liao.
However, the Northern Expedition ended in failure, which made the Song Dynasty begin to fear Liao and turn to passive defense. However, how could this Liao country let go of the Song Dynasty, continue to invade the south and plunder the resources of the Song Dynasty crazily? After the Song Dynasty, it gradually lost a large area of land resources and began to turn to peace.
However, some North Korean ministers refused to hold peace talks. For example, Kou Zhun, the new prime minister, insisted on letting Song Zhenzong go to the first battlefield to boost morale, rather than giving in to the threat of Liao. Although Song Zhenzong had given up from the bottom of his heart, he was forced to go to the battlefield to command and kill the enemy. However, the situation at that time was so severe that it was useless to resist again. Finally, Song Zhenzong sent someone to negotiate and make peace.
Song Zhenzong sent Cao Liyong, saying that it doesn't matter to give one million taels of silver, but the land in our country can't be given any more. When Kou Zhun heard about it, he said to Cao Liyong angrily, "The emperor said that one million taels of silver doesn't matter, but if it exceeds three hundred and two thousand taels, he will die." As a result of the final negotiation, the Song Dynasty paid100002 silver and 200002 silk to Liao every year, which is the specific content of the name Yuan Alliance.