From Fray Bernardino de Sahagún, Florentine Codex, Book 12, Chapter 11 (Mexica)

Here it is told how the Spaniards came to Tlaxcalla, which was [at the time] called Texcallan.

[The first part of this chapter explains how the Spaniards reached Tlaxcala. While there, the Tlaxcalans persuaded the Spaniards to attack the city of Cholula, considered to be a shrine to the idol Quetzalcoaltl. The Tlaxcalans proved to be among the most loyal of the Spanish Indian allies, who were as responsible for the conquest of America as the Spaniards.]

They [the Tlaxcalans] drove them, they proceeded to guide them. They took leave of them after they had them enter their palace. They honored them greatly, they provided them with everything they needed, and attended to them and gave them their daughters.

Then [the Spaniards] asked them: Where is Mexico? How far is it? They [the Tlaxcalans] answered them: "It is not far now." Perhaps in three days you will arrive. It is a very good place. And [the Mexicas] are very valiant, great warriors, conquerors, who go conquering everywhere."

But the Tlaxcalans in past times had been at war with, had risen up with rage and anger against the Cholullans, They [the Tlaxcalans] disliked, hated, detested them; they would have nothing to do with them. So they told [the Spaniards]: "They [the Cholullans] are very evil, and they are our enemy. Those of Cholula are as valiant as the Mexicas. They are friends of the Mexicas."

When the Spaniards heard this, they went to Cholula, taking those of Tlaxcalla and Cempoalla with them dressed for war. When they arrived, they shouted for all noblemen, rulers, captains, chiefs, and also the men of the town to assemble in the courtyard of the gods [probably of the Temple of Quetzacoatl].

When they had all gathered, [the Spaniards and their allies] blocked the entrances, all of the places where one could enter. In the first moment, people were murdered and beaten. Nothing like this was in the minds of the Cholulans. Without swords or shields they met the Spaniards. Without warning, they were treacherously and deceitfully slain. They were ambushed because the Tlaxcalans persuaded [the Spaniards] to do it.

And everything that had happened, everything that had taken place was told, was relayed to Moctezuma. Some of the messengers came, while others left; they turned around and took flight. There was no time when they did not listen, when there were no reports.

For all of the common people were filled with fright. There were frequent disturbances. It was as if the earth moved, as if the earth quaked, as if everything was spinning before ones' eyes. There was wonder.

[The rest of this chapter discusses what Cortés did after killing people in Cholula. He learned there were two roads to Tenochtitlan. The Mexicas had blocked one, hoping Cortés would take the other. Deciding that the Mexicas intended to trick him, Cortés decided to take the blocked road.]