It's well-known at this point that there are several magical schools other than Hogwarts, Beauxbaton, and Durmstrang. It's also been noted that the Triwizard Tournament probably did not continue after 1994.
Out of curiosity, is there any in-universe reason given for why the other schools weren't included in the tournament (either in its original incarnation or the 1994 not-so-greatest-hits edition) to begin with? This is putting aside the "triwizard" assumption, of course.