Mesoamerican Long Count calendar 18. Thus 0.0.1.0.0 does not represent 400 days, but rather only 360 days and 0.0.0.17.19 represents 359 days. The name "b'ak'tun" was invented by modern scholars. The numbered Long Count was no longer in use by the time the Spanish arrived in the Yucatán Peninsula, although unnumbered k'atuns and tuns were still in use. Instead the Maya were using an abbreviated Short Count. Long Count dates are written with Mesoamerican numerals, as shown on this table. A dot represents "1" while a bar equals "5". The shell glyph was used to represent the zero concept. The Long Count calendar required
Mesoamerican Long Count calendar and the 365 day Haab'. The equivalent Aztec calendars are known in Nahuatl as the tonalpohualli and Xiuhpohualli. The combination of a Haab' and a Tzolk'in date identifies a day in a combination which does not occur again for 18,980 days (52 Haab' cycles of 365 days times 73 Tzolk'in cycles of 260 days, approximately 52 years), a period known as the Calendar Round. To identify days over periods longer than this, Mesoamericans used the Long Count calendar. The Long Count calendar identifies a date by counting the number of days from a starting date that is generally calculated to