EastGermany
After WW2, in 1949 at the potsdamconference the winning countries france, england, america and russia decided to divide germany in 2 parts. Each country got one part of the former germany, being an area it controls.
While soon the three areas controlled by america, england and france did kind of reunite and formed the "federal republic of germany", the russian part was made a own country too, the "german democratic republic". It was also called eastern germany.
Eastern germany was under heavy influence of Russia and became a communistic country very soon until the only link to democracy was the part in its name.
Eastern germany soon started to seperate itself from western germany (which became more and more democratic and capitalistic, with help from england, france and most of all, america) by closing the open borders by fences, turrets dogs and most of all huge walls.
A very interesting thing about the whole situation : Just like germany got divided after the war, also Berlin, former capital of germany got divided. Since Berlin was inside the russian part of germany, the areas of Berlin being held under the control of the three western countries soon got "westberlin".
So when Eastern germany closed the border it also literally sorrounded westberlin by a huge wall, the "berlin wall".
Anyway, there is to much historical stuff to talk about, kennedy visiting westberlin and saying "I am a Berliner !" (which is a popular cake in germany, btw), eastern and western germany used as outpost and ground for the "cold war" by eastern and western spys and much more.
1989 the berlin wall fell and with it the whole communistic system of eastern germany, both parts got re-united and became "Germany" again.
But still there are lot of differences about the once eastern and the once western part of germany (both in lifestyle, wealth, political beliefs and such) and so we still talk about eastern and western germany.