v26p1
as a followup to the minor states with no war issue, this is later in the same game. Xiongnu is now studying Alchemy, and building a music school, so they've definitely passed the point of writing but are still minor civs without being at war with anyone.
so at least temporarily I had to come up with a way to communicate with them- and that is done by sending agents into their cities, then bribing the cities once enough espionage points are earned. I did this already with the Huns, who also suffered the same weird minor no war issue, and after successfully bribing one of their cities, we were now at war with them. voila, communication begins. from there, we were able to continue talking like any normal civ.