WE RECEIVED MIXED MESSAGES before setting off in Sichuan Dagu Glacier Park, a newly established preserve in Sichuan province's Great Snowy Mountains. At roughly two-thirds the size of Texas, China's fifth-largest administrative district has 87 million people (more than triple that state's population). Still, its western border lies on the edge of the Tibetan Plateau, from which the Himalayas rise, hundreds of miles to the west. At an average elevation of 14,500 feet, the Snowies remain plenty wild: We were told bandits, mad dogs, and wolves roam the place.

To complicate things, the park lies in Heishui County, one of the hardest-hit by the Wenchuan Earthquake of May 12, 2008. Heishui, which is largely inhabited by Tibetan peoples and still heavily influenced by its lama monasteries, had been officially closed to all foreigners until 2004. The earthquake had temporarily shut its borders again, and no one knew the condition of the roads and trails.

Fortunately for us, our Beijing-based guide, Anglo-Aussie expat Ed Jocelyn, 41, and his Chinese partner, Yang Xiao, also 41 and a contributor to China's edition of Outside, had recently opened Red Rock Trek and Expedition Company for adventures in western China. Ed, who has more Chinese miles under his boots than Marco Polo and had trespassed in this region in 2003, was sanguine about what lay ahead; he pointed above, where, he assured us, Tibetan lasses danced through pastures tending to their yaks, cooled by Dagu's three 10,000-year-old glaciers.

It was early July, the beginning of the rainy season, and in the village of Xia Dagu, at 9,000 feet, the clouds hung on the firs like Spanish moss. Outside the quake-fissured stone house where we'd spent the night, Womudo, a hunched and blind Tibetan, gave us yet another warning: "The bodies of dead Long Marchers found on Dagushan," he said, "were mauled by bears."This piqued my interest most of all.

I'd organized the expedition to this remote region to clear up some of the mysteries surrounding the epic trek that had brought Mao Zedong to power in the Chinese Communist Party in 1934 35 and was afterwards turned into the nation-defining myth known as the Long March. Besieged in its Jiangxi-province stronghold in southeast China by the Western-backed Nationalist forces of Chiang Kai-shek, Mao's overmatched Red First Army 86,000 men and 30 women had cut out on an October night in 1934 and simply vanished. Their plan was to regroup with other Communist forces (namely, the second and sixth army groups) 500 miles away in Hunan. But the Nationalists and allied warlord forces resisted fiercely and prevented that from happening. Instead, the First Army would march, fight, and suffer nonstop for an entire year in one of the longest and most brutal military marches in history.

Nine months and a staggering 3,000 miles after setting out, fewer than 20,000 battered First Army soldiers the rest lost to bullets, bombs, starvation, and exposure trudged into the Great Snowy Mountains. The women had served in many crucial ways on the march, from gathering food and recruiting new porters and soldiers to performing onstage for locals and troops and organizing stretcher teams to carry the sick and wounded. Three had been left behind two with wounded husbands, one to organize local militia and 27 remained. For the next two months, on the edge of the area known as "the Roof of the World," the Reds dealt with debilitating altitudes, bitter internal strife (after merging forces with the Fourth Army), and deadly uncharted high-elevation bogs. They emerged and proceeded to march another thousand miles to northern Shaanxi province, where they established a new permanent base.