to the Mexican allies as rewards for their participation in the conquest. In practice, such privileges were easily removed or sidestepped by the Spanish and the indigenous conquistadors were treated in a similar manner to the conquered natives. The Spanish engaged in a strategy of concentrating native populations in newly founded colonial towns, or reducciones (also known as congregaciones). Native resistance to the new nucleated settlements took the form of the flight of the indigenous inhabitants into inaccessible regions such as mountains and forests. Impact of Old World diseases Epidemics accidentally introduced by the Spanish included smallpox, measles and influenza. These diseases, together with typhus and yellow fever, had a major impact on Maya populations. The Old World diseases brought with the Spanish and against which the indigenous New World peoples had no resistance were a deciding factor in the conquest; the diseases crippled armies and decimated populations before battles were even fought. Their introduction was catastrophic in the Americas; it is estimated that 90% of the indigenous population had been eliminated by disease within the first century of European contact. In 1519 and 1520, before the arrival of the Spanish in the region, a number of epidemics swept through southern Guatemala. At the same time as the Spanish were occupied with the overthrow of the Aztec Empire, a devastating plague struck the Kaqchikel capital of Iximche, and the city of Qʼumarkaj, capital of the Kʼicheʼ, may also have suffered from the same epidemic. It is likely that the same combination of smallpox and a pulmonary plague swept across the entire Guatemalan Highlands. Modern knowledge of the impact of these diseases on populations with no prior exposure suggests that 33–50% of the population of the highlands perished. Population levels in the Guatemalan Highlands did not recover to their pre-conquest levels until the middle of the 20th century. In 1666 pestilence or murine typhus swept through what is now the department of Huehuetenango. Smallpox was reported in San Pedro Saloma, in 1795. At the time of the fall of Nojpetén in 1697, there are estimated to have been 60,000 Mayas living around Lake Petén Itzá, including a large number of refugees from other areas. It is estimated that 88% of them died during the first ten years of colonial rule owing to a combination of disease and war. Timeline of the conquest Conquest of the highlands The conquest of the highlands