Mongolians have a word for it: zud. A zud is a winter so harsh that animals cannot feed through the frost and ice encrusting the steppe. In the winter of 2009-10 Mongolia suffered its worst zud for nobody knows how long – "for decades", some say; or "in living memory". Ten million head of livestock are reckoned to have died.

As I gazed from the vehicle window at the stony desert steppe I wasn"t sure whether I was seeing the dramatic fallout of that zud, or whether the rib cages and skulls were the usual cull exacted by nature in this most thrillingly harsh of environments. Whatever the case, the black vultures, sitting like homeless undertakers on the scattered boulders, were making the most of it.

We were travelling through the South Gobi, the largest and most sparsely populated of the five provinces that make up the Gobi Desert. The Gobi is the No-man"s-land between China to the south and the rest of Mongolia and the Central Siberian Plateau in the north. It is also a byword for the most barren place of the imagination. But deserts, like imaginations, are invariably fertile, even this one.

The Gobi is not just sand and gravel and dead animals. It diversifies into mountains and evergreen forest and geological freak shows – including a dune system as long and high as a mountain range – and sustains an array of endangered species that includes wild ass, wild camels and snow leopards.