Simplify the following text for a Grade 11 native English-speaking person.
Original: On 22 December 1989 , the Brandenburg Gate crossing was reopened when Helmut Kohl , the West German chancellor , walked through to be greeted by Hans Modrow , the East German prime minister .
Simplified: On the 22nd of December 1989 , the Brandenburg Gate re-opened when Helmut Kohl , the West German Chancellor , walked through to be greeted by Hans Modrow , the East German Prime Minister .