On a (loosely) related note, dividing Europe to West/East (perhaps Central) is purely political (it follows Berlin Wall[1]). For example, countries of V4[2] are in the middle[3] and yet they are called Eastern Europe. Another reason might be that most of the East is covered by Russia.
1. http://en.wikipedia.org/wiki/Berlin_Wall
2. http://en.wikipedia.org/wiki/Visegrád_group
3. http://upload.wikimedia.org/wikipedia/commons/3/39/Europe_po...