This manuscript, known as the Codex Azcatitlan, most likely dates from only a few years after the arrival of the Spanish in Mexico. It recounts the history of the Aztecs (also known as the Mexica), including their migration to Tenochtitlan (forerunner of present-day Mexico City) from Aztlán, the ancient or mythical birthplace of Aztec civilization. The codex depicts the succession of Aztec rulers, the arrival of Spanish troops headed by Hernán Cortés, and the introduction of Christianity. Of all the known manuscripts recounting Aztec history, the Codex Azcatitlan is probably the most valuable and important. In contrast to other histories written later in the colonial period, it is known for the unique way in which it records indigenous memories from the pre-Hispanic past. Like other Aztec codices, it is written in pictograms. These are very carefully drawn, by a scribe who obviously was very skilled. The codex is copied on 25 folios of paper imported from Europe to Mexico in the 16th century. Each episode in the history is presented on a double folio for easier reading. On the first folio, the author introduces a group of people whom scholars have not yet identified. They could be tlatoanis, or high-level Mesoamerican rulers or heads of state. From folio 2 to folio 25, the scribe describes the migration of the Mexica tribes to the promised land of Tenochtitlan.