El Portón is a site of the Preclassic Mesoamerican civilisation, literate and thought to be Maya.
By 500 BCE, the inhabitants built terraces which allowed a more scalable population.
They dedicated the largest temple with "feasting, bloodletting, and burning of incense".
The inscriptions on a stele dateable via radiology to 400 BCE are likely in a Mayan language; if so, it is the earliest such attestation.
This Guatemala location article is a stub.