Complex sentence: The third group is Coastal Mixtecs "mixteco de la costa" whose language is closely related to that of the Low Mixtecs; they currently inhabit the Pacific slope of Oaxaca and Guerrero.
Split into simpler sentences: The third group is Coastal Mixtecs "mixteco de la costa". This group's language is closely related to that of the Low Mixtecs, and are currently inhabiting the Pacific slope of Oaxaca and Guerrero.