The 260-day calendar spread throughout the Mesoamerican cultural region and is regarded as the oldest and most important of the calendar systems, with an origin predating its first appearances in Maya inscriptions. The earliest evidence of this calendar comes from a possible day sign with a dot numeral coefficient in an Olmec-like inscription in Oxtotitlán cave dated to 800-500 BCE. Some of the next oldest calendric inscriptions are from early strata of Zapotec in the Oaxacan highlands at sites such as Monte Albán, dating from mid-1st millennium BCE. A few earlier-dated inscriptions and artifacts have what appear to be calendric glyphs, such as at San José Mogote and in the Olmec Gulf Coast region. However, either the dating method or the calendric nature of the glyphs are disputed by scholars.