The following sentence correct or not :they treated them roughly

I'm not sure if you're asking if the sentence is grammatically correct but if so then yes. But I will say that  if a reader only sees that sentence they would be confused on who they or them was since it doesn't provide background information. so in that sense it could be wrong since it confuses the reader on the subjects of the sentence. but thats only if your're trying to identify the noun of the sentence if yk what i mean

chinese civil war took place over a long period of time between 1927 and 1950. the war was interrupted when japan invaded china in 1936 and by world war ii. the war was fought between the nationalist government of china, also called the kuomintang (kmt), and the communist party of china (cpc).