SHI: So, out of Dagestan, Abkhazia, and Chechnya, I’ll going with:
Dagestani? I don’t know if it’s a real language.
There is no language called Dagestani, although it might be nice if there was. I believe there are 28 different languages spoken in that tiny republic. But Russian is the main language of interethnic communication. This is an area of frighteningly steep mountains in the towering Caucasus range, and the very tall mountains kept most of these languages isolated for a long time.
It also probably allowed a lot of strange features to develop that might have gotten ironed out of a more widely spoken language.
Like islanization in genetics where an isolated group spins out of control genetically because it’s not getting much feedback from other groups, so it takes off on its own development, and all sorts of odd things can happen genetically. The Kalash people of Northwestern Pakistan are an example of the island effect.
This is one of the insane Northeast Caucasian languages. This one is called Tsez. It’s quite famous for probably being one the hardest languages on Earth to learn. Even native speakers make mistakes pretty regularly when they speak it. There are lot of Northeast Caucasian languages spoken in Dagestan.