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.
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Deeds can't dream what dreams can do. e.e. cummings