Iris Chang wrote The Rape of Nanking about the atrocities by the Japanese army during WW2 to the city of Nanking in China. The material is so horrifying she fell into a deep depression and committed suicide. It’s worth a read if you want to learn about a mostly forgotten holocaust of WW2 in China
It’s literally the name of the book. Also, holocaust is “the destruction or slaughter on a mass scale”. Using the same term doesn’t minimize other historical events