This article from 1937 was extremely interesting to find because it confirmed several things to me.

This article from 1937 was extremely interesting to find because it confirmed several things to me. First, Anna May Wong did not end up making a Fu Manchu movie, or a film with Sessue Hayakawa, since the 1931 Daughter of the Dragon (where Hayakawa played a Chinese detective). However, in 1937, she did make a movie for Paramount with the then-unknown Phillip Ahn, Dangerous to Know. This is interesting because this confirms that the role was written for Hayakawa in mind, as were the two other movies the two did together for Paramount, Island of Lost Men and King of Chinatown. Wong’s contract with Paramount was not renewed because of the cost overruns on Island of Lost Men. 

Fun fact: Phillip Ahn is the brother of Philson Ahn, who played Prince Tallin of Saturn in the original Buck Rogers serial. Their father was a diplomat and Korean independence fighter.