When naturalists like John Muir first entered the Yosemite Valley of California in the 19th century, they marveled at the beauty of what they believed to be a pristine wilderness untouched by human hands. The truth is that the rich diversity and stunning landscapes of places like Yosemite and other natural environments in the United States were intentionally cultivated by Native Americans for thousands of years. And their greatest tool was fire.

“Fire was a constant companion, a kind of universal catalyst and technology,” says Stephen Pyne, an emeritus professor at Arizona State University, author and fire historian.

Yosemite itself was routinely burned to clear underbrush, open pasture lands, provide nutrient-rich forage for deer, and to support the growth of woodland food crops to feed and sustain what was once a large and thriving Indigenous population.

“If you look at the early photographs of Yosemite and you see the great big majestic stands of oaks, you would be led to believe that those are natural,” says Frank Kanawha Lake, a research ecologist with the USDA Forest Service, wildland firefighter and Karuk descendent.

“But those trees are a legacy of Indigenous acorn management. Those are tribal orchards that were managed for thousands of years for acorn production and for the geophytes or ‘Indian potatoes’ that grow beneath them.”

The hugely destructive seasonal wildfires that consume millions of acres of forest across the Western United States every year are mostly triggered when lightning strikes a stand of trees that’s dangerously dry from late-summer heat or drought.

While those types of natural fires have always existed, Indigenous people have also practiced what’s known as “cultural burning,” the intentional lighting of smaller, controlled fires to provide a desired cultural service, such as promoting the health of vegetation and animals that provide food, clothing, ceremonial items and more.

“[Cultural burning] links back to the tribal philosophy of fire as medicine,” says Lake. “When you prescribe it, you’re getting the right dose to maintain the abundance of productivity of all ecosystem services to support the ecology in your culture.”

Examples of Native American cultural burning can be found across the American landscape. In the Appalachian forests of the Eastern United States, the dominance of oak and chestnut trees was the product of targeted burning that resulted in vigorous re-sprouting of the desired nut crops. The iconic tall grass prairies of the Midwest were also likely cleared and maintained by Indigenous burning as pastureland for herd animals.

Anthropologists have identified at least 70 different uses of fire among Indigenous and Aboriginal peoples, including clearing travel routes, long-distance signaling, reducing pest populations like rodents and insects, and hunting.

It’s well-established that native peoples used fire to both drive and attract game herds. For example, some tribes would open up patches of grassland inside forested landscapes that drew herds of deer and elk to the protein-rich new growth every spring. In the fall, they’d burn the grass to drive animals back into the woods where the tribe overwintered. And in the spring, they’d light fires in the woods to push the animals back into the prairie.

The tribes of the northern Great Plains were some of the few to light very large fires rather than smaller, contained burns. These prairie fires—miles-long conflagrations that raged across dry grasslands—were an effective way to drive large herds of buffalo in a desired direction. Other tribes used fire to herd grasshoppers, a tasty delicacy.

Food was not the only incentive to employ fire. For some Western tribes, a consistent crop of plant materials was essential for making woven baskets. By burning patches of land, they could ensure the regrowth of the type of straight, slender shoots that made the strongest and most artistic baskets. Others used fire to cultivate specific tree species that provided roosts for woodpeckers, whose feathers were prized for ceremonial regalia.

One of the reasons why John Muir and other naturalists would have believed that the grandeur of Western America was shaped entirely by natural forces is that they had no idea how many Native Americans had once lived there. When the Spanish established missions and settlements in “Alta California” in the 18th century, they brought smallpox with them, which decimated an estimated 70 to 90 percent of the Indigenous population.

“A lot of what we think of as wilderness was a temporary artifact of the depopulation of the native people—It was a major crash,” says Pyne. “Explorers and early travelers didn’t believe that such small groups of Native Americans could make significant changes in the landscape. Well, there were a lot more of them in earlier times.”

European colonists brought with them an attitude that fire was a destructive force with no beneficial applications. Lake points out that one of the first official proclamations by a Spanish bureaucrat in California in 1793 was to outlaw “Indian burning,” which was viewed as a threat to the Spanish cattle herds and pastures.

“With attention to the widespread damage which results to the public from burning of the fields, customary up to now among both the Christian and Gentile Indians in this country, whose childishness has been unduly tolerated,” wrote Don José Joaquín de Arrillaga, “I see myself required to have the foresight to prohibit for the future…, if it be necessary, of the rigors of the law all kinds of burnings, not only in the vicinity of the towns, but even at the most remote distances … [t]o uproot this very harmful practice of setting fire to pastureland.”

Successive waves of colonists brought the same dismissive attitude toward the benefits of controlled burns, even though European farmers and herdsmen had practiced it for centuries.

“Europe’s elites treated their own farmers and pastoralists and their knowledge of fire with the same disdain,” says Pyne. “Europe had thousands of years of agriculture and they used fire very widely, but it was a mark of ‘primitivism.’ To be modern and rational, you had to find an alternative to fire.

Not everyone agreed that outlawing cultural and other controlled burns was best for America’s forests. Throughout the late-19th and early 20th century, millions of acres were destroyed by a series of deadly wildfires, many caused by sparks thrown from the new transcontinental railroad.

The trouble with fire suppression laws is that they create a buildup of “fuel” in the forests, fallen trees and drought-ridden undergrowth that feed and spread a wildfire. In the early 20th century, some forestry scientists were calling for a return to the Indigenous practices of “light-burning” to keep fuel supplies low.

Opponents of light-burning dubbed it “Paiute forestry,” meant as an insulting reference to the Paiute Indians of Nevada and California.

“The question was, ‘Do we burn like the heathen Indians or do we protect our forests and timber interests?’” says Lake.

The answer came in 1910 with one of the largest wildfires in American history. Known as the “Big Blowup” or simply the “Great Fires of 1910,” this multi-state conflagration consumed more than 3 million acres and leveled entire towns. Lake says that on one tragic day, 78 firefighters were killed by the blaze.

Rather than renewing calls for a traditional approach to forest management that incorporated cultural burning, a traumatized U.S. Forest Service doubled down on fire suppression. In response, Congress passed the Weeks Act of 1911 authorizing the government’s purchase of millions of acres of land in which all fires would be outlawed.