They all contained less info than the main article, so they were merged into it. The edits are still there in the page histories. The one with the most info was S. Drav., but all that was was a list of populations: a WP:CONTENTFORK that could cause problems in synchronizing with the language articles. There was no information on S. Drav. itself: what makes it distinctive, what defines it, its history, sound changes, different scholars' opinions on what constitutes it, etc, so it was essentially nothing more than a list and was not actually about S. Drav. The articles for the other branches were similar but had even less to them. —