Rubio Family "de nación parda"

Hi,

I am currently researching late 1600s Rubio family from Magdalena and Etzatlán in Jalisco. For the most part, this family is described as "mulatos", but a few are also described as mulatos and "de nacion parda".

This term is new to me and when google translated, it means "of brown nation" Have any of you came across this term before. Could it be referring to a specific African tribe or geographic location?

Here are a few links: Antonio Rubio Sánchez and Pedro Rubio Valenzuela.

https://www.familysearch.org/ark:/61903/3:1:939L-QB9F-93?i=49&wc=3JF8-ZNR%3A172172701%2C172172702%2C172172703&cc=1874591

https://www.familysearch.org/ark:/61903/3:1:939L-QB9F-3G?i=53&cc=1874591

Thank You
Ruben R