The Warsaw Ghetto was the largest ghetto in Nazi-occupied Europe. The Warsaw Ghetto was established on the orders of Hans Frank who was the most senior Nazi in Poland after the success of the invasion that started on September 1st 1939. On October 16th 1940. Frank ordered that all the Jews in Warsaw and the surrounding areas had to live in specified areas within the city boundaries. To begin with it is thought that about 400,000 Jews were forced to live within the ghetto. The area allocated to the Jews represented less than 3% of the whole city. With such numbers crammed into such a small space, conditions were extremely difficult. The ghetto was sealed off to the outside world on November 16th 1940.