365-day calendar 365-day calendar A 365-day calendar consists of exactly 365 days per year (no leap days), and is primarily used in computer models and as an assumption in every-day calculations. For example, a calculation of a daily rate may use an annual total divided by exactly 365. Interest rates in some banks are calculated using a 365-day calendar. Some Mesoamerican calendars used a 365-day year with no leap year, resulting in a gradual shift of the seasons relative to the calendar. This includes the Maya Haab' and the Aztec Xiuhpohualli calendars. Some versions of the Zoroastrian calendar also use a fixed
Mesoamerican chronology 850. Normally, the Classic period in Mesoamerica is characterized as the stage in which the arts, science, urbanism, architecture, and social organization reached their peak. This period was also dominated by the influence of Teotihuacan throughout the region, and the competition between the different Mesoamerican states led to continuous warfare. This period of Mesoamerican history can be divided into three phases. Early, from 250 to 550 CE; Middle, from 550 to 700; and Late, from 700 to 900. The early Classic period began with the expansion of Teotihuacan, which led to its control over the principal trade routes of northern