And now I am back in Esfahan. It is late spring and the city is blossoming with the pleasures of the season. Although many new restaurants and cafes have opened, at night the parks and squares are filled with families stretched out on rugs and tucking into tomato-and-pomegranate salads, chicken kebabs, barberry pilaf and trays of sabzi khordan, the mix of mint, tarragon, basil and other herbs eaten wrapped in flatbread with walnuts and feta. By the end of the day, even the river bank and bridges are lined with people feasting, while the upper tier of the Khaju Bridge is packed with young men and women.

One man catches my eye and reminds me why I have returned. Tall and upright, made taller by a bun-shaped, black felt hat, he is wearing a pair of baggy black trousers cinched at the waist. These are the traditional clothes of the Bakhtiari, one of the largest and most famous of Iran’s nomadic groups. I had once come across a book by Vita Sackville-West – one of several authors who travelled the tribal routes and wrote about the migration – and now I’m looking to the west and the looming Zagros mountains, towards Bakhtiari land where I am headed tomorrow.

As the westward road leaves the desert and rises into the mountains, brown gives way to green and the landscape’s true beauty emerges. So too do people selling buckets of melons, tomatoes and potatoes, and stalls piled with baggy trousers and straw hats. Beyond sleepy, tin-roofed Chelgerd, the mountains rise ever steeper. Timing is everything. Come in winter and there’s serious free-skiing to be done above the city. Go in May, as I have done, and the river rushes with snow melt, the valleys are carpeted with white, yellow and blue spring flowers, the slopes with fresh goat-thorn, and the Bakhtiari nomads are just arriving from their winter home on the west side of the mountains with their flocks and bundles. Look, there they are…

On a ridge above a valley, not far from Chelgerd, I see them walking across the Kouhrang River; on the opposite bank there is a camp where a handful of men are shearing sheep. ‘That,’ says Ali, my guide and driver, ‘is where we are staying.’ And as he says it, I can feel the tension of the journey – the entire day spent standing in the visa queue at the Iranian Embassy in London, the sleepless night flight, the lack of a room at my hotel in Esfahan – lift like a cloud over the horizon. This is exactly where I want to be staying.