If you find yourself in Ruzomberok, and want to get to Krakow and Auschwitz, you have 2 choices. 1. You have to backtrack all the way to Bratislava in far western Slovakia, and go by train from there.
2. Try the bus adventure. You can get to Poprad [mid-north Slovakia] by bus or train, then take a bus north to the Polish ski resort Zakopane, then a bus from Zakopane to Krakow.
By taking the bus, you have gone directly north instead of doing an end around trip, and saved yourself hundreds of kilometers, and lots of hours.
The train systems of Eastern European countries concentrate on tracks between large cities within the country. There were lots of restrictions at borders, so getting directly from the middle of Slovakia to the middle of Poland was not possible in the past. JC