Why is the diversity of peoples and languages so great in transcaucasia

Transcaucasia, Russian Zakavkazye, a small but densely populated region to the south of the Caucasus Mountains. It includes three independent states: Georgia in the northwest, Azerbaijan in the east, and Armenia, situated largely on a high mountainous plateau south of Georgia and west of Azerbaijan. Together these countries have an area of about 71,850 square miles (186,100 square kilometres). I hope this is right if it is not i am sorry i tried to help u.