Mixteca.

Headword: 
Mixteca.
Principal English Translation: 

a region between Puebla and Oaxaca where Mixtec people live; also, the Mixtec people (mixtecatl would be a Mixtec person, singular)

(central Mexico, 1613)
see Annals of His Time: Don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, James Lockhart, Susan Schroeder, and Doris Namala, eds. and transl. (Stanford: Stanford University Press, 2006), 246–247.

Attestations from sources in English: 

auh no oncã quiniuhti tlayacac quinmanque quiyacatihtiaque ynic tlayahualoloc in timacehualti yn mixteca tlacanechicolti yn oynnemactic yn oconanque yncapilla catca tliltique = And also for the first time they put us commoners who were Mixtecs, gathered from various places, in the lead, at the front of the procession. They have been granted and took what used to be the chapel of the blacks (central Mexico, 1613)
Annals of His Time: Don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, James Lockhart, Susan Schroeder, and Doris Namala, eds. and transl. (Stanford: Stanford University Press, 2006), 246–7.