How do you define "Historical" as genre? I saw lots of manga tagged with Historical and it turns out it didn't have anything to dor with real, history. it's just made up fictional kingdom with ancient china costume thingy. Sometimes it frustrate me when I want to search for "Real" historical manga the things came out wasnt what I expected.
golden kamuy otoyomegatari sengoku strays reiri tenju no kuni The Great Merchant Kim Manduk vinland saga
Historical means the story happens in the past. But unless it's a really researched work, the historical background is going to be simple or won't follow reality if complex. And there's historical fantasy too, past setting, but with magical stuff happening.
Many Chinese novels are marked as "Historical" which I'm not sure is really accurate. The novel setting of the current world is completely fictional, but there are actual historical elements as a distant background. The stories are set in fictional countries/dynasties surrounded by other fictional countries/dynasties. However, in most of these stories Confucius must have existed for so many Confucian ideals. Also, many of them have references to actual historical figures or dynasties (of the distant past from the viewpoint of the novel's characters). Typically, you can think of the stories as being set some time in 15th century China where the past few centuries are fictitious. I don't know if I would call such stories "historical fiction" or an "alternate timeline." The thing is, what caused the historical divergence is not focused on in these stories. You only get the sense that something happened differently in the distant past which led to the current situation.