How do landforms affect the shape of countries in europe?

Large mountain ranges can form natural boundaries between countries. Large bodies of water also form natural boundaries. This can be a river, or something as large as the English channel. The reason this occurs is due to several factors:

- the difficulty of projecting military force across large barriers like water or mountains in the days before planes, helicopters, etc.
- the cultural differences that occur between the two populations separated by the barrier (due to difficulty of communicating between the two locations - as in evolution, isolated populations develop separately and thus often differently)
- the difficulty of governing a place that is geographically distant (have to go around mountains or sail across the sea) because the people are unlike you (different cultures), it is hard to communicate with that area due to the barrier (takes time to sail across water or go around mtns), and it's difficult to project military force to control the population if necessary