The Chinese side of this production puts the issue in a very different light. The problem in Hollywood for Asian actors is that they get very few opportunities and what opportunities there are have a tendency to go to white actors. Quite obviously this isn't a problem in Chinese cinema.
There, Chinese actors dominate the industry, filling at least 90% of the cast. And because the casts of this film industry is so uniform, there is a bit of a demand for foreign talent, and so it's not uncommon to see Korean and Japanese (and Hong Konger and Taiwanese) actors playing nominally Chinese characters. In a purely Chinese production this is a bit like a Hollywood film casting a black actor to play a character who would have nominally gone to a white actor. This particular film's heritage is a bit mixed, but it's still quite clear that the primary audience is meant to be in China.
NOPE.
http://www.ew.com/article/2016/07/28/great-wall-first-look
ENTERTAINMENT WEEKLY: This is your first time working with a Hollywood studio, Universal. What has the experience been like? Does it feel like the biggest project youve ever worked on?
ZHANG YIMOU: Indeed, this is the biggest film I have worked on. Working with a Hollywood studio, I have learned a lot. Hollywood studios are very experienced in filmmaking and this is worth studying. However, there are also many differences between Hollywood and Chinese filmmaking. So in order to collaborate, good communication is important. All in all, this type of partnership allows both sides to have a deeper understanding of each other. It opens the door, creates more opportunities for the future, and builds a great foundation.
How do the films Hollywood elements blend with its Chinese elements?
First and foremost, this is an English-language film, and a Hollywood blockbuster. It was already very clear in the script phase. This is a Hollywood monster movie and needs to be made in that style. I dont want to change that approach, and theres no need to do that. What I really want is to bring Chinese color and cultural background to the worldwide audience through a film language that they are familiar with.
How much did your own Chinese identity contribute to the development of the film?
A lot. This script was written by American screenwriters. So the story is really told from an Americans perspective. When I came onboard, I wanted to make sure everything Chinese in this film feels genuine.
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You see, some people mistakenly believe this is a Chinese-language film for China with some western leads for flavor like Dragon Blade or whatever. No. This is a Chinese production made in the Hollywood system targeting the worldwide (read: western) audience, with western leads, and is entirely in English, written by Hollywood screenwriters.