In the spring, when the snow clears on the higher alps of the Himalayas, the mountainous passes between Nepal and Tibet become busy trading routes, trodden by hundreds of Nepalese farmers, who take their sheep, yak and goats on to the higher pastures, so that the animals can graze on the new grass. The livestock are fitted with saddle-packs filled with rice, which is sold on arrival in Tibet.
On the steep and stony Nara Lagna pass (the "Pass of the Blue Sheep"), a shoe's life is short and tough. If walkers ever think they've lost the trail, they only need to cast about for a broken article of footwear, and they'll be on the right track again.
Collectively, the shoes are a sorry sight: twisted and forlorn, cracked across the soles, half-buried in mud, canvas uppers severed from rubber soles. The leather boots fare better, but even they appear withered and mummified - so dark, shrivelled and dense that they could have been dug up from a peat bog.