Borders disputes mainly, both claimed ownership of Cieszyn Silesia, Orava Territory and Spiš. They fought a short war over the territory in 1919 and while the crisis was diffused by the league of nations in 1924 it continued to strain relations.

Another issue was over co-operation with the Soviet Union (they both shared land borders with Russia). Poland refused to work with their former overlords while Czechoslovakia was willing to work with them, further straining relations.

Because they had a major disputed territory between them, and tensions between the countries were high. Southwestern Poland and Czechoslovakia both used to be part of the Habsburg Austro-Hungarian Empire. While part of the same Empire, the borders between ethnic groups became fluid and populations were mixed. After the dissolution of the Empire, there was no easy way to draw a border that left all the people who wanted to live in Poland on one side and the ones who wanted to live on Czechoslovakia on the other.

In 1919, the countries fought the short Polish-Czechoslovak war, where the Czechoslovak forces stopped their attack because of pressure from Entente powers. The following treaty divided up the disputed territories so that both sides remained unsatisfied, but the majority of the disputed territories remained in Czech hands.

During the Munich conference, the Poles annexed the disputed territories.