In the Postclassic period, the Xiuhcoatl fire serpent was associated with the three concepts associated with its tail-sign: turquoise, grass, and the solar year. All three of these concepts were associated with fire in central Mexico during the Postclassic, with dry grass and the solar year being closely identified with fire and solar heat. Page 46 of the pre-Columbian Codex Borgia depicts four smoking Xiuhcoatl serpents arranged around a burning turquoise mirror. A turquoise-rimmed mirror has been found at the Maya city of Chichen Itza, with four fire serpents encircling the rim. The archaeological site of Tula has warrior columns on Mound B that bear mirrors on their backs, also surrounded by four Xiuhcoatl fire serpents.