Each year, Mr. Morgan said, he spends months plotting the route, enlisting 300 to 400 Mongolian hunting families to work the race and about 1,500 horses to carry contestants across high passes, huge valleys, wooded hills, river crossings, wetland, dunes and open steppe in extreme temperatures.

It costs about $13,700 to enter, which includes a custom-made saddle, access to a medical response team and veterinarians to care for the horses, among other expenses.

“We’ve had older riders before and they’ve struggled for various reasons,” Mr. Morgan said in an interview on Tuesday. This year, participants’ injuries included a broken collarbone, a punctured lung and a broken rib. (There were zero horse injuries.)

“The fundamental essence of an adventure has to incorporate the unknown,” Mr. Morgan said. “The most rich experiences come from this sort of slightly chaotic moments when you’re not completely prepared.”

But Mr. Long is now “a legend,” he said.

On Tuesday, Mr. Long had just returned to Boise after several long-haul flights from Ulaanbaatar , Mongolia. Reached by telephone, he said that he was getting used to sleeping in a bed again and that his gastrointestinal system was reacquainting itself to American food.

Mr. Long , who retired as the chief technology officer for a health care technology company , said he was inspired to enter the competition after watching “All the Wild Horses,” a film about the race.

“It took me about 15 minutes to decide that I could do that,” he said. He “hated” to think that he couldn’t.