The woman Josephina, represented by the character Jesusa, was born around 1900 since she was already a soldier in the 1910 Mexican Revolution and fifteen a few years after she joined her father as a soldier. The author Elena Poniatowska first meets Jesusa in 1964 when Jesusa is in her early sixties. Consequently, since the period of the Porfiriato, which was the time of Porfiriato's regime, extended almost unbroken from 1876 to 1910, Jesusa would have lived her youngest childhood during the Porfiriato.
She was born to an indigenous Indian mother (Mexica, or Aztec) and a Mexican (indigenous plus European mix) father. This put the very young Jesusa in the category of an indigenous person. At the time, Mexico had successfully begun a policy that elevated the "mestizaje," those of mixed indigenous and European cultures who rejected indigenous culture and language but identified with European Mexican culture and language, to the foundational role of forming the base of modern national Mexican identity. ("Mexican People," Wikipedia)
Since Jesusa's mother and father both identified with indigenous cultural identity and language, this put Jesusa on the wrong side of the "Indian problem." Because of her indigenous status, Jesusa, especially with dark skin that visually identified her indigenous heritage, would have been amongst those who were in the lowest sector and of the lowest social class during the Porfiriato.