Mongols once captured half the known world thanks to their fearsome light cavalry skills. In the bitterly cold Tsakhir Valley, it has long been believed that man is no one without a horse. For countless generations, the herders of the valley have protected their horses from ferocious winter storms by amassing a giant herd and nominating their bravest young men to protect it. The tradition served as a brutal coming of age ritual, until five years ago when, under increasing environmental pressure and growing urbanisation, it abruptly ended. Too many young men now believe they are nothing without Facebook.

Fearful about the loss of culture, elders vowed to revive the winter journey, and two young friends, Tsagana and Batbold, were handed the daunting responsibility to not only protect the valley’s herd, but to save its most sacred practice. For four months, the boys battle Mongolia’s deadliest winter on record, testing friendship and faith in a fight to keep 2000 horses from wolves and blizzards, and to preserve an ancient way of life. In the Iron Winter, nothing can survive alone. Their journey is as hauntingly beautiful as it is unremittingly harsh.