Weird seing it translated as Niang-Niang Seiga and Xuanwu's Ravine when the commonly accepted modern translations are Kaku Seiga and Genbu's ravine.
I believe Niang-Niang is if you read the Kanji in Seiga's name in Chinese, and Xuanwu is the Chinese name for the mythological being the ravine is named after, wheras Genbu is the Japanese name.
So both could very well be correct but nowadays the unspoken consensus is Kaku and Genbu. Pretty sure that's how the Japanese fans refer to them too.