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Anyone roaming around in Mongolia's vast and forbidden Ulaan Taiga can reasonably be assumed to be either a smuggler, a livestock rustler, or a bandit, and probably well armed.

The lawless wilderness, whose name loosely translates as "Red Forest," sprawls along the northwestern frontier with Russian Tuva. Although it was once freely traversed by migratory Tsaatan reindeer herders, who foraged and hunted and grazed their animals there (and dabbled in a little horse rustling and smuggling themselves), Mongolian authorities booted everyone about 30 years ago and declared the region off-limits except by special permit. Criminal gangs in Tuva couldn't have cared less, and their cross-border raids have persisted. Today the Tsaatan's ancestral homeland—as much a physical realm as a parallel spirit world known to shamans as "the Dark Heavens"—is a perilous no-man's-land where shootouts between mounted rangers and Tuvan desperadoes occur regularly, particularly along a notorious trail that intersects the border at a sacred mountain called Uma Tolgoi. This was to be our expedition's objective.

We would be a large team of 23 people and 38 horses under the leadership of Hamid Sardar-Afkhami, a rakish 44-year-old Iranian-American scholar and documentary filmmaker who divides his time between Mongolia and Paris. Cosmopolitan and well-connected, Sardar grew up in privileged circumstances in the Shah's Iran and, after his family fled the 1979 Iranian revolution, in France and the Unites States, attending prep school at Choate Rosemary Hall, in Connecticut. But in the extremes of Mongolia's outback he's as tough as boot leather. He could be a model for Indiana Jones, right down to his beat-up Stetson fedora. He has a Ph.D. from Harvard in Sanskrit and Tibetan studies and has been a practicing Buddhist for nearly 25 years, pursuing a rigorous tantric discipline called Dzogchen.

Sardar's explorations have taken him to the far corners of Tibet and Mongolia to investigate occult mysteries of Central Asia's supernatural landscapes. These demanding odysseys have been carried out in the spirit of religious pilgrimages, or what Sardar calls "Buddhist adventures," the idea being to embrace danger and fear as a path to self-awareness. During the 1990s, for example, he and author Ian Baker made repeated forays into Tibet's three-mile-deep Tsangpo Gorge to explore a hidden land called Pemako. They never found its fabled innermost sanctuary, but in 1998, after thrashing around the leech-ridden jungle for weeks, they did locate a thundering waterfall that had been rumored to exist for more than a century. The discovery made headlines around the world (EXPLORERS FIND ELUSIVE SHANGRI-LA IN WORLD'S DEEPEST KNOWN GORGE), but to Sardar the hoopla missed the point of a pilgrimage, which is all about an inward journey.

I first met Sardar in Nepal in 1999, and I later traveled with him in Tibet. We stayed in touch only sporadically afterwards, and not much at all after he moved to Mongolia's capital, Ulaan Bator, in 2000 to start a cultural-immersion program for American college students. He remained something of a mysterious character to me even as he discovered his calling as a filmmaker and ethnographic photographer. His first three films earned top honors at the Banff Mountain Film Festival, and his large-scale platinum prints command upwards of $5,000 in Paris art galleries. Inspired by the work of Edward Curtis, who photographed the great tribes of the American West, Sardar is on a mission to make a visual record of Mongolia's nomadic people before they vanish into the 21st century. Outfitting groups like ours and operating an exclusive tented camp is just a "summer hobby," he says, but also a "skillful means" to achieve his ends.

We would be among the first Western adventurers to explore the Ulaan Taiga since Mongolia drew back the Iron Curtain in the late 1980s. The expedition he proposed was a challenging two-week pack trip, starting at his isolated camp west of Lake Hovsgol, in a valley where the grasslands rise up to meet the taiga (alpine forests). From there we would ride to a Tsaatan encampment of tepees and hook up with a shaman and several hunters, then head off into a shadowy world inhabited by bear, elk, moose, and wolves... and the ghosts of Tsaatan ancestors. Only the shaman would know the way, and he'd have to divine our route to avoid hazards.

Our goal—geographically speaking, anyway—would be to traverse the Ulaan Taiga's high country, a sponge cake of peat bogs, lakes, and streams enveloped by forested mountains. This is the watershed for five major rivers, as well as the portal to the Dark Heavens, which Sardar describes as "a twilight world of lights, sounds, and voices."