A Calendar Round date is a date that gives both the Tzolkʼin and Haabʼ. This date will repeat after 52 Haabʼ years or 18,980 days, a Calendar Round. For example, the current creation started on 4 Ahau 8 Kumkʼu. When this date recurs it is known as a Calendar Round completion. Arithmetically, the duration of the Calendar Round is the
least common multiple of 260 and 365; 18,980 is 73 × 260 Tzolkʼin days and 52 × 365 Haabʼ days. Not every possible combination of Tzolkʼin and Haabʼ can occur. For Tzolkʼin days Imix, Kimi, Chuwen and Kibʼ, the Haabʼ day can only be 4, 9, 14 or 19; for Ikʼ, Manikʼ, Ebʼ and Kabʼan, the Haabʼ day can only be 0, 5, 10 or 15; for Akbʼalʼ, Lamat, Bʼen and Etzʼnabʼ, the Haabʼ day can only be 1, 6, 11 or 16; for Kʼan, Muluk, Ix and Kawak, the Haabʼ day can only be 2, 7, 12 or 17; and for Chikchan, Ok, Men and Ajaw, the Haabʼ day can only be 3, 8, 13 or 18.
Year Bearer A "Year Bearer" is a
Tzolkʼin day name that occurs on 0Pop, the first day of the
Haabʼ. Since there are 20 Tzolkʼin day names, 365 days in the Haabʼ, and the remainder of 365 divided by 20 is 5 (), the Tzolkʼin day name for each successive 0Pop will be 5 later in the cycle of Tzolk'in day names. Similarly, since there are 13 Tzolk'in day numbers, and the remainder of 365 divided by 13 is 1 (), the Tzolk'in day number for each successive 0Pop will be 1 greater than before. As such, the sequence of Tzolk'in dates corresponding to the Haab' date 0Pop are as follows: Thus, the Year Bearers are the four Tzolkʼin day names that appear in this sequence: Ik', Manik', Eb', and Kab'an. "Year Bearer" literally translates a Maya concept. Its importance resides in two facts. For one, the four years headed by the Year Bearers are named after them and share their characteristics; therefore, they also have their own prognostications and patron deities. Moreover, since the Year Bearers are geographically identified with boundary markers or mountains, they help define the local community. The classic system of Year Bearers described above is found at Tikal and in the
Dresden Codex. During the Late Classic period a different set of Year Bearers was in use in Campeche. In this system, the Year Bearers were the
Tzolkʼin that coincided with 1 Pop. These were Akʼbʼal, Lamat, Bʼen and Edznab. During the Post-Classic period in Yucatán a third system was in use. In this system the Year Bearers were the days that coincided with 2 Pop: Kʼan, Muluc, Ix and Kawak. This system is found in the Chronicle of Oxkutzcab. In addition, just before the Spanish conquest in Mayapan the Maya began to number the days of the Haabʼ from 1 to 20. In this system the Year Bearers are the same as in the 1 Pop – Campeche system. The Classic Year Bearer system is still in use in the Guatemalan highlands and in Veracruz, Oaxaca and Chiapas, Mexico. ==Long Count== Since Calendar Round dates repeat every 18,980 days, approximately 52 solar years, the cycle repeats roughly once each lifetime, so a more refined method of dating was needed if history was to be recorded accurately. To specify dates over periods longer than 52 years, Mesoamericans used the Long Count calendar. The Maya name for a day was
kʼin. Twenty of these kʼins are known as a
winal or
uinal. Eighteen winals make one
tun. Twenty tuns are known as a
kʼatun. Twenty kʼatuns make a
bʼakʼtun. The Long Count calendar identifies a date by counting the number of days from the Maya creation date 4 Ahaw, 8 Kumkʼu (August 11, 3114 BC in the
proleptic Gregorian calendar or September 6 in the
Julian calendar -3113 astronomical dating). But instead of using a base-10 (
decimal) scheme, the Long Count days were tallied in a modified base-20 scheme. Thus 0.0.0.1.5 is equal to 25 and 0.0.0.2.0 is equal to 40. As the winal unit resets after only counting to 18, the Long Count consistently uses base-20 only if the tun is considered the primary unit of measurement, not the kʼin; with the kʼin and winal units being the number of days in the tun. The Long Count 0.0.1.0.0 represents 360 days, rather than the 400 in a purely base-20 (
vigesimal) count. There are also four rarely used higher-order cycles:
piktun,
kalabtun,
kʼinchiltun, and
alautun. Since the Long Count dates are unambiguous, the Long Count was particularly well suited to use on monuments. The monumental inscriptions would not only include the 5 digits of the Long Count, but would also include the two tzolkʼin characters followed by the two haabʼ characters. Misinterpretation of the
Mesoamerican Long Count calendar was the basis for a popular belief that a
cataclysm would take place on December 21, 2012. December 21, 2012 was simply the day that the calendar went to the next
bʼakʼtun, at Long Count 13.0.0.0.0. The date of the start of the next b'ak'tun (Long Count 14.0.0.0.0) is March 26, 2407. The date of the start of the next
piktun (a complete series of 20 bʼakʼtuns), at Long Count 1.0.0.0.0.0, is October 13, 4772. ==Supplementary Series==