The Wizarding World, 1933 - After Gellert Grindelwald tried to burn down Paris in 1927 and could only be stopped by some of the most powerful magicians, he has been on the rise. All over continental Europe, which is affected most, but also America, Asia, Africa and Australia, people have long started worrying about the increasing number of magical terrorist attacks in the whole world. But not everybody is scared - numerous people start believing in "For The Greater Good", Grindelwald's justification for his actions, and his followers, the Acolytes, are multifying. 

Great Britain, 1933 - There is one country, however, that has been left unscathed so far: Great Britain, the home of Albus Dumbledore, Grindelwald's former best friend and leader of the Resistance against the Acolytes, who is tied to him by blood. Therefore, the dark wizard is not able to enter the island.
Although the International Confederation of Wizard has declared a state of emergency, British Minister of Magic Hector Fawley has different concerns. He is only interested in the survival of the so-called Magical Commonwealth, an alliance between Great Britain and the countries which belong to the British Empire in the Muggle World*. Officially, their magical counterparts are equal partners in politics and economy, but there are a lot of British Wizards who secretly believe that they are superior. Together, they form an underground group called British Supremacists, which is also opposed to the traditional pureblood society, whose members believe in the independency of magical politics from the Muggle World.
Anyway, while the Magical Commonwealth is still intact, the British muggles are struggling to keep their Empire together, as the British muggle economy is weakened as a consequence of World War I. Meanwhile, politicians are trying to appease the Nationalist Forces that are rising in Muggle Germany. 
Because of all this mess, Fawley has decided to strengthen the Magical Commonwealth by inviting students from all over it to Hogwarts. At the same time, after having recognized that it is safe from Grindelwald, more and more international witches wizards are moving to the island and send there children there, too. A truly international student body is developing at Hogwarts.

*Countries which belong to the British Empire in 1933: Bahamas, Bechuanaland Protectorate, British Malaya, Ceylon, Cyprus, Falkland Islands, Hong Kong, India, Kenya, Malta, Mandatory Palestine, Nigeria, Northern Rhodesia, Southern Rhodesia, Sudan, Tanganyika, Trinidad and Tobago