It turns out we were looking at different tents. Ali leads me to one on our side of the water which at least has the advantage of the big view, a huge scope of the river, grasses, and what I now see are several separate nomad camps with corrals for goats and sheep, the stony slopes above them. Above the green there is a large stripe of brown rock; above it, the zigzag of the snowy, jagged ridge; above that, a perfect deep-blue sky. It is an epic landscape to inspire an epic journey, but first there is lunch.

We cross the fast river over a skinny flattened pipe that serves as a bridge and walk up to two tents: a round one serving as the family home and an open­-sided rectangular one into which I am welcomed by a man stoking coals and grilling lamb kebabs. In Bakhtiari land, men share the cooking.

His name is Siyavash, after a great Persian hero, and he is assisted on the grill by a solid man with a grizzled, stubbled face, Groucho Marx moustache and an impressive name: Jehangir, ‘conqueror of the world’. A plastic sheet is laid over the carpet in the tent and, together with Siyavash’s father and his cousin Habib, I eat salads, rice, yogurt and the succulent lamb, talk about migration, summer in the valley and the glories and tribulations of the Bakhtiari. Then I follow the old man’s example and allow the altitude – we are above 2,500 metres – a full belly, the flat clank of sheep bells, birdsong, the babbling of the river and a bubbling sense of happiness lull me to sleep. When I wake, he is talking to two older women, while three younger ones sit on the opposite side of the tent, a small child between them. Two of these women – wearing colourful headscarves to indicate they are unmarried – signal me to put my head down again and sleep some more. When I do finally wake, I walk downstream a little and sit alone, and stare some more.

If I were a photographer, I would want to capture the shifting of late shadows across the snow mountains, and the diamond glitter of the river through the valley. If I were a composer, I would try to harmonise the constant running of water with the clunking of stones as they drag along the riverbed, the buzzing of bees, the whistling and whooping of men as the flocks are brought in for the night. But I am a writer, and sitting barefoot and slightly sun-struck, I note the clarity of the sky and a chill descending as the light fades. Late that night, with nomad tents glowing across the liver and the moon full overhead, I fall asleep trying to remember Byron’s lines: ‘Not vainly did the early Persian make/His altar the high places and the peak… there to seek The Spirit…’