After hearing of the Spanish conquest of the Aztec Empire and having the native population much diminished by an epidemic of smallpox, the "cazonci" Tangaxuan II pledged his allegiance as a vassal of the King of Spain without a fight in 1525. It is believed that the Spanish conquistador Cristóbal de Olid, upon arriving in the Tarascan State, now in present-day Michoacán, explored some parts of Guanajuato in the early 1520s. A legend relates of a 16- or 17-year-old Purépecha, Princess Eréndira, who led her people into a fierce war against the Spanish. Using stolen Spanish horses, her people learned to ride into battle. In 1529 to 1530, the Spanish forces entered Michoacán and some parts of Guanajuato with an army of 500 Spanish soldiers and more than 10,000 Indian warriors.