From The Amur River: Between Russia and China, by Colin Thubron (Harper, 2021), Kindle pp. 7-10:
The source of great rivers is often obscure. They descend in a confusion of tributaries, or seep from inaccessible swamps and glaciers. The Indus is born from six contested streams. The Danube, it is claimed, issues from a gutter in the Black Forest. As for the origins of the Amur, when a conclave of geographers from Russia and China met to debate it, they found to their chagrin that its farthest source lay in neither country, but in these remote Mongolian mountains. My horsemen know the river only as the Onon, the ‘Holy Mother’; but if the mother herself is born somewhere, few but Ganpurev know quite where this is, and he has been there only once, ten years ago.
The horses are not used to this. They are the heirs of nomad cavalry, bred for the steppes. Riding them, you forget anything you’ve been taught. I no longer rein in the White Horse when he nuzzles the buttocks of the packhorse in front. And you spur them forward not with your heels but with a hissing Chu-chuh. You never fondle their heads. As we reach higher ground we start to go faster, with relief. But the preferred gait of the White Horse is not a leisurely canter but a fast trot. For mile after mile he insists on this jarring bustle for which the Western rider’s inured rise-and-fall in the saddle is hopeless – the tempo is too fast – and instead you stand in your stirrups as the Mongol raiders did.
Here the shadows of the past are older, deeper. For this is the Mongol heartland. Eight hundred years ago Genghis Khan decreed the upper valleys of the Onon and Kherlen rivers an inviolable sanctuary, permitted only to Mongol royalty, sealed off for their private rites and burial. It became the spiritual powerhouse of his vast empire. Even now, Batmonkh says, travellers to these mountains are resented. This is holy land. Somewhere to our east, a forested massif lifts to the rocky pate of Khan Khenti, revered as Burkhan Khaldun, on whose slopes the young Genghis Khan, destitute and alone, found a haven from his tribal enemies. On these protective heights, runs the Mongol epic, he sheltered as poor as a grasshopper, and later faced the mountain in grateful worship – a mountain already sacred to his people, close to the Eternal Blue Sky of their ancestral veneration. To this mountain, too, he dedicated the worship of his descendants for ever, and himself returned in times of crisis to breathe again its primal power.
The true site of Burkhan Khaldun is unsure, but beyond us, in the watershed of the Onon, its valley fills with the adversities of the future conqueror. Here, in about 1162, he was born into the clan of a minor chief. On its banks, after his people had abandoned her, his mother dug for roots to keep her children alive, while the boys fished its streams; and here, after escaping from imprisonment by enemy raiders, Genghis submerged himself in the Onon waters, keeping his head afloat in the wooden halter by which they had confined him, then slipped away.