Original: The former borough of Mitte, located entirely within the former East Berlin, was combined with the boroughs of Wedding and Tiergarten (both of which belonged to West Berlin) to form the new Mitte borough.
Simplified: Mitte was the most central locality of Berlin (Mitte is German for center). It was set up in 1920, when GroÃ - Berlin was set up, and in 2001 it was joined with Wedding and Tiergarten to make a new borough called Bezirk Mitte.