The Haab, the Maya civil calendar, divided the solar year into eighteen months of twenty days each, three hundred and sixty days in total, and then appended five further days to bring the count to three hundred and sixty five. Those five days did not belong to any of the eighteen named months and carried no month name of their own, and Maya tradition treated that structural oddity as more than a bookkeeping detail: a period genuinely outside the ordered, named time that governed the rest of the year, and therefore a period in which the protections ordinary time offered no longer applied.
The Postclassic Dresden Codex, one of the few Maya bark-paper books to survive Spanish destruction, devotes a sequence of pages to Wayeb rites keyed to which of the four possible days could open the coming new year, each paired with its own year-bearer deity, associated omens and a set of ritual actions, including carrying an effigy of the relevant deity between shrines positioned at the cardinal directions. Sources describing the period consistently associate it with heightened danger: avoidance of travel, of settling disputes, of beginning new undertakings, and a general expectation of misfortune for anyone who treated the five days as ordinary.