Basically, it's about a place which he would have known about -- a strategic fort that changed hands twice during Justinian's endless Persian war (see second paragraph of the 'history' section of the Wikipedia article I link). I read that history when I looked it up for the current connotation (see other two links), and thought, 'Wow, people from Sal's WIP would have known the place, and, come to think of it, somebody from Carolin's WIP might have, too -- and the Gothic leaders would have known about it, following the news from the Persian front. Only, for any of them, the name wasn't Sukhumi yet.'

Hence, the post with the names...