In Piros and Prehistory, David Leedom Shaul turns his attention to the Piro language, once spoken by the people of the Piro pueblos in New Mexico but extinct since approximately the year 1900. While arguments have been made in favor of Piro belonging to the Tiwa branch of the Tanoan family, Shaul counters this classification with a detailed rebuttal, firmly establishing Piro within the Tanoan family but outside of the Tiwa branch.

Shaul’s arguments use linguistic analyses coupled with historic and prehistoric records of migration and cultural interaction. Following the establishment of Piro as a Tanoan language, much of the linguistic analysis involves determining the aspects of Piro that were inherited from the earlier Proto-Tanoan versus those that were incorporated later as a result of borrowing from other languages through cultural interaction. This book lays out the linguistic argument that the similarities between Piro and Tiwan languages result from borrowing, not common ancestry, and it provides a record of contact between groups and linguistic evolution based on these movements.