The Chilam Balam texts treat chiefly of history (both pre-Spanish and colonial), calendrics, astrology and herbal medicine. Written in the Yucatec Maya language (in European script), the manuscripts stem from the 18th and 19th centuries, although many of the texts that found their way into these books date back to the time of the Spanish conquest. It is assumed that in the earliest books, the element of prophecy came to the fore more strongly.
Whereas the medical texts are quite matter-of-factual, the historical and astrological texts belong to esoteric lore. At various places in these texts, important bits of information about early mythology crop up. Apart from their intrinsic value, the historical texts (or chronicles) are particularly important since they have been cast in the framework of the native Maya calendar (although with adaptations to the European calendrical system) and contain ancient tun and katun predictions. Reconstructing Postclassic Yucatec history from these data has proven to be an arduous task.
Due to their often allusive, metaphorical nature and the archaic Yucatec used, the Chilam Balam texts offer a formidable challenge to translators. The quality of existing translations varies greatly, those of Barrera Vásquez & Rendón, Reifler Bricker & Miram, and Roys counting among the best.