Russia, ___, Egypt, Kazakhstan, USA, Azerbaijan, Georgia. (In order of most commonly seen when looking this up)
Some might debate it. Maybe some other countries like Iceland are part of the list
Hint 1 is referring to tectonic plates (kinda)
It's about continents...
There are 7 countries in this list that are the most commonly given when you search for this. Here are 6.
There are probably around 3-10 Wikipedia articles about this