Andean religion is known in unusual detail, and the detail exists because the colonial church set out to eradicate it and kept notes.
The extirpation of idolatry campaigns in the Peruvian viceroyalty sent inspectors through the highlands to identify shrines, mummified ancestors and the specialists who served them, and to record what was found before destroying it. The resulting files describe the huacas of particular valleys, the offerings made to them and the calendar they were made on, at a level of local specificity that no devotional literature would have produced.
Alongside them sit the chroniclers. Spanish accounts of Inca religion were written by soldiers, officials and clergy; Garcilaso de la Vega, of Inca and Spanish parentage, wrote to defend the dignity of his mother's people; Guaman Poma produced a long illustrated letter to the Spanish king denouncing colonial rule from an Andean point of view. The ceque system of ritual lines radiating from Cusco is known chiefly through a seventeenth-century Jesuit account.
Every one of these witnesses is writing after the conquest and inside its arguments.
The Inca administration's own records are the missing piece. Khipu, the knotted cord device used for accounting and possibly for more, is not read. Whether any khipu encodes narrative rather than number is an open question, and if it does, the Andes hold the only unread archive of a state religion in this atlas.