This is Total War! achievement question

[RedGuard]

So if I were to play Dong Zhou, would I have to release the Han immediately and attack them the same turn, as well as turn on Ma Teng, or does this achievement only count factions you don't have preexisting diplomacy with?

In the past it used to be a lot simpler ala Rome 2 where everyone is already neutral and ready for war with each other from turn 1. but just making sure the conditions of the old games still apply.

It just seems like it would be an epic campaign to play as Dong Zhou on legendary and at war with everyone despite how hard it would be

[RedGuard]

yeah just so everyone knows, you won't get this is Total War! achievement as Dong Zhou, as you start out with the Han as your vassal and can't release them on turn 1, while at the same time you are incapable of maintaining that vassalage for the whole game as eventually you will abdicate the emperor in order to win the campaign.