From the production company's instagram:

"Our series is a Chinese ancient costume drama adapted from the IP of the well-known Chinese author Shui Qiancheng. It is invested, produced and distributed by a Thai company, directed by a director from Taiwan, China, and jointly produced by the art and costume team of mainland China."

- The drama is available to watch on Viki, iQIYI, GagaOOlala, and on Youtube for free at a slower release schedule. Both Chinese and Thai dubs are available for this series. - 

The character for whom the Thai actor is portraying is quite small tho, in the drama. But he is a significant character in the novel. Nevertheless, this is still a Chinese drama (Chinese culture, setting, costumes with a plot based on a Chinese novel with Chinese actors) and should be listed as such. But it is what it is.