Artifacts, such as stone tools, pottery, and other objects, indicate that people lived in the southwestern United States as early as 10,500 years ago. At that time, small bands of people who lived from the land on available game and plant foods occupied the area. For several thousand years the population grew and agriculture developed in what is now Arizona. Cultural groups eventually formed, such as the Hohokam ("ho-ho-kam"), Mogollon ("muggy-YOHN") and those such as the Hopi to the north who constructed Pueblos (called puebloan communities). These groups interacted with each other and moved, when necessary, in search of food, firewood and other resources. In the mid 1100s, interaction between the Hohokam, who lived in the Tonto Basin area, and groups native to northern Arizona banded together to create a culture later called Salado, named for the nearby Rio Salado, or Salt River. Occupation of the area by the Salado people is thought to have ended around A.D. 1450. Most researchers believe that eventually some residents of Tonto Basin roamed north to join the puebloan tribes, others moved south to join what is now the Tohono O'Odham nation, and still others returned to hunting animals and gathering plants. Apaches moved into the area in the 1500s and are still nearby today.

Once Europeans arrived, Spain ruled the region from the 16th century until Mexico proclaimed its independence in 1821, after which Mexico governed the area until the mid 19th century. Land aquired by the United States from Mexico at the conclusion of the Mexican War in 1848 included Arizona. In combination with the territory added by the Louisiana Purchase of 1803, this land vastly expanded the boundaries of the nation. Reports of fertile soil and abundant natural resources in the West quickly reached the eastern United States, which had been hit hard by the economic depressions of 1818 and 1839. The promise of affordable land and new opportunities opened floodgates to the West. Waves of new settlers poured in, displacing and driving away the American Indians who had lived there for centuries. Calling it "manifest destiny," some of the country's leaders and many of its people believed they had an obligation to expand the nation's boundaries all the way to the Pacific Ocean.

Explorers, adventurers, ranchers, miners and settlers in search of natural resources or new homes penetrated the far and remote reaches of the newly opened Southwest lands. Some of these early visitors stumbled upon a few of the hundreds of ancient ruins protected for centuries by their isolation and inaccessibility. Some of these multilevel, stone apartment-style and platform-mound dwellings were once home to the American Indians of the Salado culture.

Word of discoveries spread quickly, inciting both national and international fascination with the culture and art of America's first settlers. Exhibitors, museums and private collectors alike created a demand for authentic American Indian objects. Museums sought artifacts to study and share with the public through exhibitions. Although sites were often systematically investigated, excavators were not held to stringent scientific or professional standards. Some treasure hunters, unhampered by laws or regulations, plundered ancient sites causing extensive damage and destruction. Without regulatory laws, irreplaceable American Indian artifacts became part of permanent collections in museums and private homes, both domestic and foreign.

During the late 19th century, anthropology and archeology gained a foothold in the curriculum of universities and with influential thinkers of the time. (Anthropology is the study of the origins and social relationships of human beings, and archeology is the study of past human life and culture by the recovery and examination of remaining artifacts.) Alarmed at the deteriorating state of the nation's ancient irreplaceable cultural resources, preservationists and conservationists called for legislation to protect them. One of the first sites protected by that legislation, known as the Antiquities Act of 1906, was Tonto National Monument, which was established as a national monument on December 19, 1907 by President Theodore Roosevelt.