but much less so. Other post-classic cultures such as the Aztec did not have fully developed writing systems, but instead used semasiographic writing. Mixtec writing The Mixtec writing emerged during the 13th century, much later than the systems previously mentioned. Mixtec is a semasiographic system that was used by the pre-Hispanic Mixtecs. Many of its characteristics were later adopted by the Mexica and Mixteca-Puebla writing systems. The origin of the Mixteca-Puebla is the subject of debate amongst experts. The Mixtec writing system consisted of a set of figurative signs and symbols that served as guides for storytellers as they recounted legends. These storytellers were usually priests and other members of the Mixtec upper class. Mixtec writing has been categorized as being a mixture of pictorial and logographic, rather than a complete logogram system. Mixtec writing has been preserved through various archaeological artifacts that have survived the passage of time and the destruction of the Spanish conquest. Among these objects are four pre-Hispanic codices written on tanned deer skin covered with stucco. These codices are read in boustrophedon, a zigzag style in which the reader follows red lines that indicate the way to read. Most of the current knowledge about the writing of the Mixtecans is due to the work of Alfonso Caso, who undertook the task of deciphering the code based on a set of pre-Columbian and colonial documents of the Mixtec culture. Although the Mixtecs had a set of symbols that allowed them to record historical dates, they did not use the long count calendar characteristic of other southeast Mesoamerican writing systems. Instead, the codices that have been preserved record historical events of this pre-Columbian people, especially those events related to expansionism in the era of Ocho Venado, lord of Tilantongo. Aztec writing The Aztec writing system is adopted from writing systems used in Central Mexico. It is related to Mixtec writing and both are thought to descend from Zapotec writing. The Aztecs used semasiographic writing, although they have been said to be slowly developing phonetic principles in their writing by the use of the rebus principle. Aztec name glyphs for example, do combine logographic elements with phonetic readings. Post-Columbian Period When Europeans arrived in the 16th century, they found several writing systems in use that drew from Olmec, Zapotec, and Teotihuacano traditions. Books and other written material were commonplace in Mesoamerica when Hernán Cortés arrived in 1519. Archaeologists