Analysis of the iconography in a directional almanac on Codex Borgia pages 49–52 invites comparison with almanacs in a related set of divinatory manuscripts known as the Borgia Group, but one aspect of the Codex Borgia almanac remains unique. It records real-time dates employing the central Mexican system of year dates that help identify the images as year-end rituals. These fifteenth-century dates correlate with the last twenty-day “month” in the year, known as Izcalli in the Valley of Mexico and neighboring Tlaxcala. Izcalli rituals in February involved drilling a new fire, the erection of sacred trees, and animal sacrifice, all of which appear on Borgia 49–52. During Izcalli, human sacrifice was performed only every fourth year, a pattern like that seen in the Codex Borgia and the Codex Cospi, where death imagery and decapitated humans appear prominently on the fourth year-bearer page, associated with the southern direction. Borgia Group codices also depict trees and birds representing the four cardinal directions. These are most prominent on Codex Fejérváry-Mayer page 1 in a cosmogram representing two different calendar formats, like those seen in the Borgia almanac. The 5 × 52-day format was used to measure the solar year and Venus cycle, and a second set of day signs appears in a 4 × 65-day pattern useful in calculating the fifty-two-year cycle and the Venus cycle. This provides a subtext for understanding the dates represented on Borgia 49–52 and the extension of the almanac on page 53, where the Venus almanac begins.
