I think ancient times and marriage are the best political means. Every dynasty, there will always be friction with other countries on the border, and other countries on the border will try their best to occupy the territory and hurt the people on the border. However, the war between the two countries is solved by marriage. A period of peaceful coexistence between the two countries can save the people from the suffering of the war, the people can recuperate, and the country's military strength can be restored within a period of time. In my opinion, there are these reasons for peace:

The affinity between the two countries is the most cost-effective and convenient way to obtain peace for a period of time among various political means in ancient times. In ancient times, sending troops directly to attack and counterattack was not only a matter of consuming national strength, but also needed a lot of manpower and material resources to support marching and fighting. At the same time, the people will suffer from war, displacement and even an uprising that will disrupt the state power. Therefore, reconciliation is the most convenient and quick political means to quell the war between the two countries, and at the same time it consumes the least national strength. Therefore, those in power who pursue peace will marry their royal princess to a foreign country in exchange for temporary peace.

The affinity between the two countries can give the country precious breathing space and time to recuperate. The two countries have been at war for a long time, and their national strength is easy to be empty, which will also have an impact on the regime at that time. Only through friendly relations can the country get a short respite, vigorously develop agriculture and restore productivity, and have the strongest guarantee for the next foreign invasion. At the same time, there will be a long period of rest and recuperation, so that the country will enter a period of peace and tranquility, the people will live and work in peace and contentment, and social unrest will be reduced, which is conducive to national stability.