I know that this wouldn't be cannon, but I've been playing a "simulation" of sorts where my friends and I had spawned in eastern Akavir in a valley by the ocean. We haven't run into any Tseci but we have encountered Ko Po Tun and Kamal. I know that we have 1 Kamal trader (I have no idea how that works because 1, its giant and 2, there's barely peace between us since they killed my former "secretary") but mostly, the other encounters have involved a Kamal throwing an ice bolder at my friends tower effectively destroying it haha. The most history I know so far though, is the Ko Po Tun.
The simulation has us currently in late Mertheric era, last time I saw it was about 0E, 5200 or so. The Ko Po Tun are currently having a civil war, I have no idea what caused it or what it's about, but I know that at first there were 3 factions, the Ko, Po, and Tun, and more recently it's been the Ko, P, O and Tun. Currently, my kingdom of Acetros is at war with the Tun after they failed to invade us, we've fought them back twice now. They seem to be "honor fighters," attacking through the front of our city. Arrows pretty much one shot their soldiers and they're weak to fire and also they had very basic armor, but recently they developed "heavy" troops which wear ninja armor along with poison darts.
Other than that, I know the Tseci are pretty friendly for now, like, they aren't eating humans yet (I have no idea when and if they will come for us because we are "Akavir Men") and I'm also worried the Dwemer are going to try and take our land to make a highway through our town, as an earlier game, when we were a Dwemer colony, they mentioned building through the area we're in.
By no means is this cannon, I just thought it might be interesting to add to the lore since the game makes characters and such pretty accurate.
Thank you for taking the time to read it all and if I remember I'll upload some updates.
Have you read the pages on the Wiki about it? They have decent information on the topic. If you need a loremaster to talk to you about it, consider asking one here on the wiki, such as User:Dovahsebrom.