You're right that there is a well-established term "Southeast Europe" to refer to the countries you mention: https://en.wikipedia.org/wiki/Southeast_Europe http

You're right that there is a well-established term "Southeast Europe" to refer to the countries you mention: https://en.wikipedia.org/wiki/Southeast_Europe https://en.wikipedia.org/wiki/Southeast_Europe But there is also the fact that Europe continues far to the east of those parts, so there is another southeast corner somewhere else.