<P> It was necessary for Cortés to rebuild his alliances after his escape from Tenochtitlan before he could try again to take the city . He started with the Tlaxcalans . Tlaxcala was an autonomous state, and a fierce enemy of the Aztecs . Another strong motivation to join forces with the Spanish was that Tlaxcala was encircled by Aztec tributaries . The Tlaxcalans could have crushed the Spaniards at this point or turned them over to the Aztecs . In fact, the Aztecs sent emissaries promising peace and prosperity if they would do just that . The Tlaxcalan leaders rebuffed the overtures of the Aztec emissaries, deciding to continue their friendship with Cortés . </P> <P> Cortés managed to negotiate an alliance; however, the Tlaxcalans required heavy concessions from Cortés for their continued support, which he was to provide after they defeated the Aztecs . They expected the Spanish to pay for their supplies, to have the city of Cholula, an equal share of any of the spoils, the right to build a citadel in Tenochtitlan, and finally, to be exempted from any future tribute . Cortés was willing to promise anything in the name of the King of Spain, and agreed to their demands . The Spanish did complain about having to pay for their food and water with their gold and other jewels with which they had escaped Tenochtitlan . The Spanish authorities would later disown this treaty with the Tlaxcalans after the fall of Tenochtitlan . </P> <P> Cortés needed to gain other new allies as well . If the Spaniards were able to prove they could protect their new allies from the possibility of Aztec retribution, changing sides would not be too difficult for other tributaries . After Cortés's forces managed to defeat the smaller armies of some Aztec tributary states, Tepeyac, and later, Yauhtepec and Cuauhnahuac were easily won over . Cortés also used political maneuvering to assure the allegiance of other states, such as Tetzcoco . In addition, Cortés replaced kings with those who he knew would be loyal to him . Cortés now controlled many major towns, which simultaneously bolstered Cortés's forces while weakening the Aztecs . </P> <P> Though the largest group of indigenous allies were Tlaxcalans, the Huexotzinco, Atlixco, Tliliuhqui - Tepecs, Tetzcocans, Chalca, Alcohua and Tepanecs were all important allies as well, and had all been previously subjugated by the Aztecs . </P>

What were the effects of smallpox on the population of tenochtitlan