When Francisco Coronado and the Spaniards first explored the Rio Grande Valley in 1540, in modern New Mexico, some of the chieftains complained of new diseases that affected their tribes. Cabeza de Vaca reported that in 1528, when the Spanish landed in Texas, "half the natives died from a disease of the bowels and blamed us." When the Spanish conquistadors arrived in the Incan empire, a large portion of the population had already died in a smallpox epidemic. The first epidemic was recorded in 1529 and killed the emperor Huayna Capac, the father of Atahualpa. Further epidemics of smallpox broke out in 1533, 1535, 1558 and 1565, as well as typhus in 1546, influenza in 1558, diphtheria in 1614 and measles in 1618.