In learning a little about the People's Crusade and the First Crusade, it seems Hungary is important as a sort of gateway to the east. The crusades must pass through Hungary in order to get to the east, and must even apparently convince a well guarded gate to let them pass through the country.
Similarly, in modern times, I recall it being an important gateway, this time from the east, with refugees needing to pass through it in order to get to Europe.
So why is Hungary so important for travel between the west and east? I don't see any obvious reason why it should be, looking at a map.