Their valley was the initial route to New Mexico and West Texas explored by Spanish conquistadors in the 1500s. In the mid-1600s, the Juntans began engaging in long-distance migrant labor in Nueva Vizcaya, and in the 1680s they began inviting Franciscan missionaries and serving as important military allies to Hispanic troops.

Yet for seventy-five years only the missionaries, without any Hispanic military or civilians, lived among them, due to both the remoteness of their valley from Hispanic settlements and the Juntans' insistence upon their autonomy. This is unique in Spanish colonial annals on the northern frontier of New Spain.

This detailed research study adds much new information and many corrections to the rare previous studies.