K i'm Chinese and is quiet familiar with our own long history, if suppose a future total war would focus on China, my suggestion...

Most people would probably think of the 3 kingdoms period right off the bat when they consider a total war for China, but IMHO that's not nearly as good as one done for the eastern Zhou period (Spring and Autumn+ warring states) start from the fall of western zhou in 771 b.c to the Qin's final conquest in 221 b.c

There are a variety of reasons to why this period is the best for total war.

1.Time span: 3 kingdom period isn't long at all.. even if you start from the yellow turban rebllion the period is still less than 100 years, while this period lasted 450 years.

2. Factions: many faction fell and emerge in this period... in fact... totaling over hundreds of them existed durign this period... but for more major influencial once there was still well over 20-30 in this whole period while the same can't be said for the 3 kingdoms. not to meantion these factions were much more unique than the 3 kingdom periods.

3.School of thoughts: probably one of the biggest reason why this age is the best, during this time many influencial schools of thoughts emerged and playd a great part to shape this entire era and even Chinese history as a whole (such as confucism and daoism or legalist) they could work as relgion worked in MTW, but would be even more interesting as rulers were free to choose and switch whom they listened to or followed. (or even accept multiple amounts of them) and these schools often choose their own.. meaning they could withdraw support from those they deem do not really listen to them. in fact you could probably make it to work so they will bestow special units/buildings/techs etc if you follow them etc....

4.Warfare: I think one of the key spirit behind the total war series is the change in warfare... however warfare changed little during the 3 kingdoms period just the same things with different implementation... while during this period tactics/weapon/technologies all seen great changes (from teh emergence of crossbows and cavalry, to the abandoning of chariots... to the gradual switch to iron etc...)

5.Agents: this is probably the most famous period for assasian in the entire chinese history.... spies and emmisaries stories were also incrediablly common.
Just some food for thoughts.