For more than 100 years beginning in 1540, the Pueblo Indians of present-day New Mexico were subjected to successive waves of soldiers, missionaries, and settlers. These encounters, referred to as the Entradas, were characterized by violent confrontations between Spanish colonists and Pueblo peoples. The Tiguex War, fought in the winter of 1540-41 by the expedition of Francisco Vásquez de Coronado against the twelve or thirteen pueblos of Tiwa Indians, was particularly destructive to Pueblo and Spanish relations. In 1598 Juan de Oñate led 129 soldiers and 10 Franciscan Catholic priests plus a large number of women, children, servants, slaves, and livestock into the Rio Grande valley of New Mexico. There were at the time approximately 40,000 Pueblo Indians inhabiting the region. Oñate put down a revolt at Acoma Pueblo by killing and enslaving hundreds of the Indians and sentencing all men 25 or older to have their foot cut off. The Acoma Massacre would instill fear of the Spanish in the region for years to come, though Franciscan missionaries were assigned to several of the Pueblo towns to Christianize the natives.

Based on the above article, answer a question. Who had occupied the Rio Grande?
Pueblo Indians