These bowls are made by ceramic artisans in Santo Domingo Tonaltepec, Oaxaca, Mexico.
The pottery from Tonaltepec has a unique appearance. Pieces are fired inside a stone oven which may have pre-Hispanic origins. Afterwards, they are dyed with spontaneous and expressive splashes of tannin pigment. Due to their organic nature, the stains tend to vanish over time.
Historians can often date the production of certain pieces according to how much the stains have faded.