Sources and Research History
Two categories of sources of the ritual practice of time of the Pre-Europe- an/pre-Christian 365-day calendar are available for the researcher: The postclassic codices and colonial accounts of the Yucatec 365-day calendar.
The Postclassic Codices
The primary source to the postclassic Yucatec 365-day calendar rituals are the codices. Only fourreadable postclassic Maya codices—Codex Dresden, Codex Paris, Codex Madrid or Codex Tro-Cortesianus and Codex Grolier— are known to have survived.  The discovery and publication of these codices has proven to be very valuable in the study of Maya religious philosophy and practices. Codex Dresden, Codex Madrid and Codex Paris, but, though, not the Codex Grolier, composes scenes depicting and describing Yucatec New Year ceremonies of the 365-day calendar. The New Year ritual is delineated on pages 19-20 in Codex Paris, on pages 34-37 in Codex Madrid? and on pages 25-28 in Codex Dresden (fig. 7 & 8). The so-called “New Year pages” of these three codices illustrates the Calendar Round series of 52 Year Bearers (cf. below about the concept “Year Bearer”).
Cyrus Thomas was one of the first scholars who employed both pre- European/pre-Christian and colonial sources in order to analyse Maya history and culture. In his article from 1882, Thomas observed a correspondence with the description of the New Year festival in the book Relacion de las cosas de Yucatan (c. 1566) by the Spanish Bishop Fray Diego de Landa and two passages of the Codex Madrid and Codex Dresden. William E. Gates found later that pages 19 and 20 of Codex Paris depicted the beginning of the New Year (Taube 1988: 1-2; 253; 356-257). The New Year pages of these three codices outline deities and not human religious specialists. It must therefore be emphasised that they were ritual divine models of the proceedings, and not actually delineating the proper New Year ritual. The postclassic Maya codices were consequently ritual guides or manuals, containing short cryptic texts, where deity performers act as instructors modelling how to conduct a ceremony. For example a diagram by Coe and Chase of the Wayeb-rituals recorded by Landa resembling pages 75-76 of Codex Madrid convey that ritual specialist used codice as handbooks (Love 1986: 200; 202-204, fig. 14 & 15 & 16).
Codex Madrid, Codex Dresden and Codex Paris have many passages in common but they embody also different scenes partly because they derive from various periods and regions. The existing codices were all produced in the postclassic period, except Codex Grolier, of Yucatan. Codex Dresden dates from the early postclassic period (c. 900 AD - c. 1250 AD. whereas Codex Paris and Codex Madrid originate from the Late postclassic period (c. 1250 AD - 1521 ad) (Taube 1988: 218). Taube asserts that the provenance of Codex Dresden, Codex Madrid and Codex Paris from Yucatan, Mexico is exhibited by the fact that they contain logosyllabic inscriptions mainly in Yucatec, which is also the language used by the Indigenous descendants of the peninsula of Yucatan today.  Moreover, Taube argues that certain calendar conventions, like a k’atun cycle and a puuc shift in Year Bearers, imagery of natural and social phenomena typical of the Yucatan region, and corresponding accounts by Landa of the Yucatec New Year rituals, contribute to indicate a Yucatec origin of these manuscripts. The Codex Dresden, Codex Madrid and Codex Paris outline accordingly a Yucatec postclassic (e.g. Pre-European/Pre-Christian) New Year Ceremony of the 365- day calendar (Taube 1988: 14).
-  Poor fragments of codices from the classic period have been found in Waxaktun, SanAgustin Acasaguastlan, Nebaj, Altun Ja and Mirador. The remains of the classic codices are,however, in such a bad condition that they cannot be interpreted (Taube 1992: 1).
-  See Taube for more information about Codex Grolier (1988: 16, note 5).
-  Cf. the encyclopediacal work of astronomy and calendars in Maya codices by Brickerand Bricker (2011).
-  Cassandra R.Bill, Christine L. Hernandez and Victoria R. Bricker claim to have identified three sets of almanacs which pages are related to the New Year ceremonies on pages34-37 of Codex Madrid. These are the upper and middle region of pages 52-53, 54-55b and84c-88c (Bill, Hernandez and Bricker 2000: 158-165).
-  Thomas, Cyrus. A Study of the Manuscript Troano. U.S. Department of the Interior:Contributions to North American Ethnology, vol. 5: 1-237. Washington D.C. 1882.
-  Gates, William E. Commentary upon the Maya-Tzental Perez Codex with a ConcludingNote upon the Linguistic Problem of the Maya Glyphs. Paper of the Peabody Museum ofAmerican Archaeology and Ethnology, Vol. VI, no. 1. Harvard University, Cambridge, Mass.1910.
-  Data from archaeology and epigraphy show that the Indigenous people of the Peninsula of Yucatan spoke Yucatec at least in the late classic period (Taube 1988: 23).
-  The colonial sources of the New Year festival of the Yucatec have been collected,systematised and analysed by Karl A. Taube in his seminal Ph.D. dissertation from 1988(1988: 269-301).