Pack horses laden with trekking equipment cross the Konze La on the Hidden Valleys trek, Ladakh, India, Asia

Pack horses in the Ladakh region, Himalayas, India, Asia

Pack horses cross a small pass near Goyul along the Lasa to Gasa trekking route, Bhutan, Himalayas, Asia

A cowboy wrangler leads a pack train of horses up the South Kaibab Trail in Grand Canyon National Park, UNESCO World Heritage Site, Arizona, United States of America, North America

Pack mules reflected in a water puddle in golden evening light, Lang Tang village, Himalayas, Nepal, Asia

Caravan of pack horses, Yurutse valley,Hemis National Park,Ladakh region, state of Jammu and Kashmir,India,Asia

Pack horses at Rumbak village,Hemis National Park,Ladakh region, state of Jammu and Kashmir,India,Asia

Pack horses in front of a turquoise mountain lodge with Lang Tang village in background, Himalayas, Nepal, Asia

Khyber Pass area, Pakistan, Asia

Pack horses on their way down cross a wire bridge, Tzum Valley, Nepal, Asia

Portrait of a young man walking two loaded horses along road, near Pare Pare, Sulawesi, Indonesia, Southeast Asia, Asia

Swing bridge made of steel over Dudh Koshi river, Solukhumbu, Khumbu, Mount Everest region, Nepal

Supply of Willersalpe alp only by horses, Hinterstein, Hintersteiner Valley, Bad Hindelang, Allgaeu, Bavaria, Germany, Europe

Supply of Willersalpe alp only by horses, Hinterstein, Hintersteiner Valley, Bad Hindelang, Allgaeu, Bavaria, Germany, Europe

Female hiker waits for pack horses to pass on the South Kaibab Trail in Grand Canyon National Park north of Williams, Arizona May 2011. The South Kaibab Trail starts on the south rim of the Colorado Plateau and follows a ridge out to Skeleton Point allowing for 360-degree views of the canyon then down to the Colorado River. At the Colorado River the trail connects with the North Kaibab trail as part of the Arizona Trail system, that crosses the state of Arizona from Mexico to Utah.

Portraits are of John Indrehus (with his pack horses) and outfitter Wayne Fairchild ( with white baseball cap) of Lewis and Clark Trail Adventures, on the Lolo Trail in Idaho between Wendover Creek and Snow Camp.

Horses are led through the mountains at King's Canyon National Park, California, United States of America

Horses and riders lead a string of pack animals near Sixty Lake Basin in King's Canyon National Park, California, USA, California, United States of America

Wild horses