https://www.cambridge.org/core/journals/antiquity/article/megafortresses-in-the-south-caucasus-new-data-from-southern-georgia/7752B2551034811556C96E75E909D730#
Bronze and/or early Iron Age, not securely linked to any known state or people.
Link posted by Bill Armintrout over on TNE.
I found that fascinating - not least because the extensive fortress described is only one of many from that place and period.