You can’t see it, but somewhere in the approaching sand cloud is one of the longest trains in the world: It’s one-and-a-half miles (2.5 km) long. It’s impossible to discern anything in the jostle of passengers and the rasping dust the train has kicked up as it rolls toward us through the Sahara Desert.

The freight cars pass for what seems an eternity, the train gradually slowing until, at last, with a shuddering halt, the two passenger carriages reach the station of Nouadhibou, formerly Port Etienne, with a population of 90,000, Mauritania’s second-largest city and commercial center.

Those who have not yet jumped into the passing freight cars stake their claim on the last of them, while the others mass outside the passenger carriages. There are men in turbans, women in billowing dresses, young children, enormous bundles, rugs, bleating goats and enough pushing and shoving for a rock concert. They all want to board at the same time — through the same door.

Woman with goats near Atar, Mauritania

I make the mistake of stepping back to take photographs. I escape the bedlam and am hopelessly shunted to the end of the line. It soon becomes clear that many of these people are not embarking. They are husbands, family or friends assisting others in getting on, but inadvertently adding to the confusion. And I cannot get past them.

They also have every reason to panic — the train only stops for a few minutes. A woman in a pink dress finally hauls me into the carriage by seizing my backpack, while her husband pushes me by my buttocks from behind. Just as I am launched inside, the train lurches violently and we plod off into the heart of the Sahara.

The Iron Ore Express shuttles people and ore from the desert to the coast on a single-track railway line of 419 miles (674 km).

The ore is the bedrock of the Mauritanian economy, but the train is just as important to the people, providing a means of transport out of remote communities and access to the outside world.

Three trains run daily between the mines in Zouérat to the Atlantic port of Nouadhibou, and one of these carries passengers. Passengers can ride for free on the iron ore or pay a few dollars for the “luxury” of a hard wooden seat in the carriages. These can be hopelessly overcrowded.

Once the train picks up speed to a maximum of 31 mph (50 km/h), it also gathers the sand from the desert — which explains why I could hardly see the train until it was right in the station.

There is not a single foreigner on the train besides me, and only four other women. I am the object of much interest, although the men visibly relax when I say I am meeting “my husband” in a few days time.

I sit with the lady in the pink dress and share her biscuits and the drool of her one-year-old son. I can only communicate with her by smiles and nods.

Outside is frontier country. It’s hard to believe this lunar-like landscape was once full of lakes, rivers and vegetation. We pass the odd herd of goats, but our only other view is a sandy track that occasionally appears, following the railway line.

La Mauritanie, the land of the Moors, claimed independence from its French colonial rulers in 1960. While you can still find baguettes and croissants at the breakfast table and children who will ask “Donnez-moi un cadeau” (give me a present), the Moorish culture is still by far the more dominant.

Mauritania is almost twice as big as France. Three-quarters of it is desert. With a population of only three million people, it does not even come close to the 11 million living in the greater Parisian metropolitan area alone.

The railway line was built at about the same time as the country’s independence, to take advantage of the sizeable iron-ore deposits in Zouérat. The railway line and the port are close to the territory of Western Sahara, which was disputed between Morocco and Mauritania since nationalism emerged in the 1960s, when nomadic Saharans settled in the region.

The nationalist Polisario Front (mostly Berber inhabitants of the region) waged guerrilla warfare and sabotaged the train until 1979, when the Mauritanian government renounced its claims to the land.