Gorkhi-Terelj is a national park an hour and a half east of Ulaanbaatar, in Mongolia, where granite boulders the size of houses rise out of open steppe and larch forest along the Tuul River, at the edge of the mountains that Mongolians hold as the birthplace of Chinggis Khaan. It is the piece of Mongolia that people reach first: green meadows in summer, white felt gers scattered across them, herds of horses and yaks, and the grey tors standing over everything, the best-known of them Turtle Rock, a boulder shaped so exactly like a turtle that it needs no explaining. The way to see it is on a horse. Herding families rent stocky Mongolian horses and ride out across the grassland with visitors, letting the animals pick their own line through the river, and the riding is the way the valley was always crossed; ox carts do the same at walking pace. A scramble up one of the granite outcrops opens the whole of Terelj beneath you, meadows, gers and dark ridges of larch running to the horizon.
On a hillside above the valley stands the Aryapala meditation temple, a small Buddhist temple built in the shape of an elephant's head, reached by 108 stone steps laid out to trace the curl of its trunk, with the valley spread below the door. The nights are the other reason: camps of gers tucked against the granite, where the tors hold the last of the day's warmth, the wood stove ticks down to nothing by dawn and the stars are as thick as anywhere on Earth. Behind the park lies the Khan Khentii wilderness, strictly protected and largely closed, holding brown bears, wolves and red deer where the Siberian forest meets the steppe, and Terelj is as far in as most people get. The road out from the capital passes a silver Chinggis Khaan on horseback, 40 metres high and built from 250 tonnes of stainless steel. Terelj is Mongolia in a day, and the horse is how you meet it.