Tlaloc is among the oldest and most widely attested deities of central Mexico, his cult and iconography, the goggle eyed, fanged rain god face, traceable in the archaeological record to Teotihuacan and beyond, centuries before the Mexica rose to power and adopted him as one of the two gods, alongside Huitzilopochtli, honoured at the templo mayor's twin shrines in Tenochtitlan. He rules Tlalocan, a paradise of abundant green described in Sahagun's account as the destination for those who died by drowning, lightning, or certain diseases the Mexica associated with water and dampness, a select company spared the longer, harder journey through Mictlan that awaited most of the dead. He commanded the tlaloque, a company of lesser rain spirits stationed at the four directions and on mountaintops, understood as pouring rain from great jars at his direction, and shrines to Tlaloc on mountain summits across the Basin of Mexico, most famously atop Mount Tlaloc itself, received pilgrimage and offering tied to the agricultural calendar.
Sahagun's account of the Atlcahualo festival early in the solar year describes child sacrifice offered to Tlaloc and to the tlaloque, the children's tears read as an omen of the coming rains, a practice recorded plainly in the Florentine Codex and one of the more difficult passages in the source material to read, though it is attested rather than invented and belongs in any honest account of his cult.