So, in China's history, one of the most important eras of a significant civil war, which has much of their classical literature devoted to the era, was the Three Kingdoms, inspiring legendary cultural work such as 'Romance of the Three Kingdoms'. It's an interesting competition between three states - Wei, Shu and Wu - to form a dynasty as an empire of these, inevitably becoming the Jin dynasty. I think it would be highly appealing to Chinese players for inclusion as a choice between hundreds of eras, it's very culturally significant to them and highly romantized. Incidentally, the Yuan dynasty could be an interesting choice of a China unified via Mongolia!

https://vignette.wikia.nocookie.net/thethreekingdoms/images/4/43/Map_of_Three_Kingdoms_%28English%29.jpg/revision/latest?cb=20100503092050 (Map of Era Politically)
https://en.wikipedia.org/wiki/Three_Kingdoms (Era)
https://en.wikipedia.org/wiki/Romance_of_the_Three_Kingdoms (Fiction about Era)