The Proto-Tepiman speech community—that is, the community that spoke the language ancestral to all the contemporary Tepiman languages—can be located at the northern end of the present-day Tepiman range, perhaps as far north and west as the Gila-Colorado confluence, and probably within the Hohokam region, during the Hohokam time period in the first millennium A.D. Evidence for the northern location of Proto-Tepiman includes, first, attestation of language contact with Proto-River Yuman, including data from phonology, syntax, and lexicon. This evidence suggests that the Hohokam were a multi-ethnic community; we present evidence that by the fourteenth century this multi-ethnic system probably included speakers of Zuni. Second, the greatest internal diversity in Tepiman is among the northernmost varieties. Third, we can reconstruct a word meaning “saguaro cactus,” a plant not found south of Ciudad Obregón, Sonora, for Proto-Tepiman. While the linguistic evidence strongly suggests the involvement of the Proto-Tepiman speech community in the Hohokam system, the evidence provided by contemporary Upper Piman languages (Akimel O’odham [Pima] and Tohono O’odham [Papago]) neither confirms nor excludes the involvement of speakers of these languages in the core Hohokam complex in the late prehistoric period.