SALT LAKE CITY — For more than 50 years, rancher Waldo Wilcox kept most outsiders off his land and the secret under wraps: a string of ancient settlements thousands of years old in near perfect condition.

Hidden deep inside eastern Utah's nearly inaccessible Book Cliffs region, 130 miles southeast of Salt Lake City, the prehistoric villages run for 12 miles along Range Creek, where Wilcox guarded hundreds of rock art panels, cliffside granaries, pit houses and rock shelters, some exposing mummified remains of long-ago inhabitants.

The sites were occupied for at least 3,000 years until they were abandoned more than 1,000 years ago, when the Fremont people mysteriously vanished. The Fremont, a collection of hunter-gatherers and farmers, preceded more modern American Indian tribes on the Colorado Plateau.

What sets this ancient site apart from other, better-known ones in Utah, Arizona or Colorado is that it's been left virtually untouched, with arrowheads and pottery shards still covering the ground in places.

‘‘I didn't let people go in there to destroy it,'' said Wilcox, 74, whose parents bought the ranch in 1951 and threw up a gate to the rugged canyon. ‘‘The less people know about this, the better.''

But the secret is out after federal and state governments paid Wilcox $2.5 million for the 4,200-acre ranch, which is surrounded by wilderness study lands. The state took ownership earlier this year but hasn't decided yet how to control public access, said Kevin Conway, director of the Utah Division of Wildlife Resources.

State archaeologist Kevin Jones said the site escaped looters to showcase a glimpse of ancient life only now being catalogued by the Utah Museum of Natural History.

‘‘It's a national treasure. There may not be another place like it in the continental 48 states,'' Museum curator Duncan Metcalfe said Thursday by satellite phone from the site.

Metcalfe said a team of researchers has documented about 200 pristine sites occupied as many as 4,500 years ago, ‘‘and we've only looked in a few places.'' In places the ground is littered with arrowheads, arrow shafts, beads and pottery.

‘‘It's a legacy that dropped in our laps,'' said Jones, who was overcome on his first visit in July 2002. ‘‘It was just like walking into a different world.''

Wilcox said, ‘‘It's like being the first white man in there, the way I kept it. There's no place like it left.'' He said some skeletons have been exposed by shifting winds under dry ledges.

‘‘They were little people, the ones I've seen dug up. They were wrapped like Egyptians, in strips of beaver skin and cedar board, preserved as perfect,'' he said.

Range Creek sustained ancient people in the canyon until it possibly dried up in a drought worse than the one now turning six years old in the interior West, Wilcox said.

The creek, which starts as a 10,000-foot alpine stream and dumps into the Green River, still runs year-round with abundant trout, shaded by cottonwood and box elder trees. Douglas fir covers the canyon sides.

The canyon would have been rich in wildfire: elk, deer, bighorn sheep, bear, mountain lions, wild turkeys — all animals that Wilcox says are still around, but in lesser numbers due to modern hunting pressure in the larger Book Cliffs region.

Although the University of Utah hired a seasonal caretaker and students from three Utah schools are working the sites this summer, Wilcox worries about possible looting, especially at odd times of the year when nobody may be watching the ranch. He said he gave it up on a promise of protection from the San Francisco-based Trust for Public Land, which transferred the ranch to public ownership.