One of the most daunting stage directions of the 20th Century comes in Peter Shaffer’s 1964 play, The Royal Hunt of the Sun. It reads simply, ‘They cross the Andes.’ I knew the designer of the original production, Michael Annals, and I regret that I never asked him, before his death in 1990, how he turned that simple direction into a stage full of Spanish conquistadores struggling through high altitude snow and ice. Probably, he didn’t. When faced with the impossible, it’s usually best to leave almost everything to the imagination, as with Shakespeare’s most famous stage direction from The Winter’s Tale, ‘Exit, pursued by a bear.’ A man in a fur coat just doesn’t do the business.

Crossing a mountain range must be a messy and dangerous pursuit. Pizarro crossed the Andes to reach Peru with fewer than 200 men. It was a daring military manoeuvre but pales into insignificance beside Hannibal’s great crossing of the Alps in 218 BC, with nearly 30,000 soldiers, horsemen, and elephants. And yet, ever since, controversy has raged about the route Hannibal and his Carthaginian army took. You would think that such an enormous mass of men and beasts would leave their mark on the landscape.

But, in fact, it’s the mess they left behind that may be about to decide the issue. Archaeologists working in a high pass above Bourg-St-Maurice –  Col de la Traversette – have found layers of bog that appear to have been churned by the passage of thousands of men and animals,. They’ve also found bacteria and parasites that live in the guts of horses. These layers have been carbon-dated to 200 BC, lending more credibility to the theory. It will only take the finding of some coins, bus tickets, buckles or weapons to decide the issue once and for all. The problem, I suppose, is that most of what men carried two thousand years ago, was perishable.

Turner’s version of ‘They cross the Alps’.

The pass is close to the ski resorts of Val d’Isere and Tignes. When you’re skiing in the Alps, as I am this week, surrounded by all the paraphernalia of the sport – the lifts, the high-altitude restaurants, the emergency helicopters, the easy access roads – pretending to yourself that you’re doing something effortful and daring, you have no sense at all of how these mountains must have appeared to Hannibal’s men and of how impossible an obstacle they must have seemed.

Archaeologists of the future, though, will have far more to go on, most of it plastic or metal. What will they make of the Elvis I see from my bedroom window?

I’m close, in Solden, in the Otztal valley in Austria, to the pass where Otzi the Iceman, Europe’s oldest mummified man, was found in 1991. Otzi probably died from a blow to the head in a skirmish with his enemies whilst crossing the Alps nearly 5,300 years ago. His body and the arrows he carried bear the DNA of several other humans. It must have been a nasty encounter. Crossing the Alps was a dangerous game.