The Sobaipuri were one of many indigenous groups occupying Sonora and what is now Arizona at the time Europeans first entered the American Southwest. They were a Piman or O'odham group who occupied southern Arizona and northern Sonora (the Pimería Alta) in the 15th–19th centuries. They were a subgroup of the O'odham or Pima, surviving members of which include the residents of San Xavier del Bac which is now part of the Tohono O'odham Nation and the Akimel O'odham.
Debate sometimes still arises as to whether the Sobaipuri and other O'odham groups are related to the prehistoric Hohokam who occupied a portion of the same geographic area and were present until about the 15th century. This question is sometimes phrased as the "Hohokam-Pima" or "Salado-Pima continuum", a phraseology that questions whether there is a connection between the prehistoric Hohokam and the first historic groups cited in the area. A key piece of the puzzle has recently been found when it was discovered that there was Sobaipuri (O'odham) present in the late prehistoric period (Seymour 2007a, 2011a, 2011b, 2014). Chronometric dates from multiple sites on the San Pedro and Santa Cruz rivers have produced evidence of Sobaipuri occupation in the 14th century (Seymour 2007, 2008, 2011a, 2011b) and some even earlier, perhaps as early as the 13th century. The position is no longer defensible that no one was present after 1400 CE [clarification needed] and that there was a substantial population decline in the prehistoric period (Seymour 2007c,d, 2011a, 2011b). Traditional stories help confirm the idea that there was likely a clash between the newly arriving O'odham, including the Sobaipuri-O'odham and the extant groups including the Hohokam and Western Puebloan groups. The issue of a continuum is implausible because archaeological and oral histories demonstrate [examples needed] that the local residents intermixed with and became O'odham.[citation needed]