Coahuilteco

Coahuilteco was a language of the Texas-Coahuila border region, spoken across what is now southern Texas in the United States and northeastern Coahuila in Mexico. It is generally treated as a language isolate, though some researchers have proposed linking it with other small languages of the region in a Pakawan family. Most of what survives of the language comes from an 88-page religious manual published in 1760, which records grammatical features such as subject-object concord and center-embedded relative clauses, along with a sound system that included ejective consonants and a length distinction in its vowels; the language is generally considered to have gone extinct by the eighteenth century.