Álvar Núñez Cabeza de Vaca was a Spaniard who had an epic journey through the Southwest from 1528 for about an 8 year period. They eventually were re-united with their Spanish brethren in Mexico. The time frame is the same, I don't know if this is the group you are talking about. De Vaca wrote of his journey after his return to Spain. Hope this helps.
Deeds can't dream what dreams can do. e.e. cummings