"Their language was called Tlashkala: no, it was not spoken right along the Reach: far from it. Another nation lived say fifty miles westward, and they could not understand it at all."
--Patrick O'Brian, Blue at the Mizzen, 170
I immediately wondered if this word is linguistically related to Tlaxcala, the people who lived in what is now Mexico when Hernan Cortés arrived--they allied with him to fight the Aztecs. But as the people in the novel who speak Tlashcala are in the southern tip of South America, I'm not sure if they are related.