The first thing AlUla asks of a visitor is patience. The valley lies in the north-west of Saudi Arabia, a long corridor of sandstone and date palms, and it reveals itself slowly: a wall of rock turning from ochre to rose, a line of tombs cut into a cliff two thousand years ago, an oasis that has been cultivated for thousands of years. What to wear in AlUla follows from that pace. This is a place for garments that are quiet, covered and made from natural materials.

The season opens in October, when the heat of the Arabian summer lifts. Days remain warm, often in the low thirties at midday, and the air is dry enough that shade feels like a different climate. Evenings cool quickly once the sun drops behind the rock, and by December and January the desert night is properly cold. A wardrobe for AlUla is therefore built in two registers: light and open for the day, layered and long-sleeved after dark.

Saudi Arabia asks visitors to dress modestly in public, and AlUla is no exception. For men and women alike that means shoulders and knees covered, and a loose line rather than a close one. Linen was made for this arrangement. A long-sleeved shirt in certified Belgian linen covers the arm while letting air move across it, which in dry heat is often more comfortable than bare skin under direct sun. The fabric stands slightly away from the body. It does not cling, and it does not announce itself.

The morning usually belongs to Hegra, the Nabataean city that became Saudi Arabia's first UNESCO World Heritage Site in 2008. Visits cross open ground between the tombs, with little shade and a great deal of pale sand. For him, the Laos Long Sleeve Linen Shirt in Oyster or Beige Cream sits naturally against that landscape, worn with the PP Casual Linen Trousers in Oatmeal. The sleeves roll back once the sun is high; the seashell buttons catch the light without asking for it. For her, the PP linen blouse, cut to the hip with a long sleeve, gives the coverage the setting asks for when worn with a long skirt of her own. In Sky Blue or Orchid it brings one note of colour to a landscape that is otherwise entirely mineral.

By late afternoon the valley turns inward. The mudbrick lanes of AlUla Old Town, lived in for centuries and now carefully restored, fill with people walking between small galleries, cafés and stalls of dates and citrus from the oasis. Close by, the heritage trail runs under the palms beside old irrigation channels, several degrees cooler than the open road. This is the easiest hour of the day, and a short sleeve is at home in it: the Laos Short Sleeve Linen Shirt in Vanille or Dubarry, with long linen trousers rather than shorts. For her, the PP linen blouse with a long skirt or long loose trousers of her own carries the same unhurried quality.

Evening in AlUla has two landmarks. One is Jabal AlFil, the Elephant Rock, where low seating is set into the sand and the stone is lit as the sky darkens. The other is Maraya, the mirrored concert hall in the Ashar Valley, whose walls reflect the canyon so completely that the building almost disappears. Both call for a little more structure. The Bliss linen shirt in Dark Blue or Vanille gives a man a clean, long-sleeved line for dinner or a performance. The Monte-Carlo Male shirt in Oyster, with its walnut buttons, does the same in a warmer tone. From late December, when the Winter at Tantora season fills the valley's calendar, bring a layer for the walk back. The temperature after ten o'clock surprises anyone who spent the afternoon in the sun.

There is a practical side to all of this. Desert dust is fine and pale, and it settles on everything. The natural tones of the collection, Oyster, Oatmeal and Beige Cream, sit close to the colour of the ground itself, and a shirt shaken out at the door is ready for the evening. The crease that forms through a day of walking and of sitting on low cushions belongs to the cloth and needs no apology. In this landscape it simply looks right. Those travelling on from the valley will find the same principles in Riyadh and along the Red Sea coast.

AlUla rewards restraint. The rock does the speaking; the visitor's part is to move through it lightly, covered, in fabric that came from a field of flax and will one day return to the earth. Every PP garment is handmade in the Dubai atelier and in Belgium from natural materials, biodegradable by design. The atelier and the valley sit on the same peninsula, and they share an understanding of heat.

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