The history of smallpox in Mexico spans approximately 500 years from the arrival of the Spanish to the official eradication in 1951. It was brought to Mexico by those in Spanish ships, then spread to the center of Mexico, where it became a significant factor in the fall of Tenochtitlan. During the colonial period, there were major epidemic outbreaks which led to the implementation of sanitary and preventive policy. The introduction of smallpox vaccination in New Spain by Francisco Javier de Balmis and the work of Ignacio Bartolache reduced the mortality and morbidity of the disease.