“Afghanistan is the most foreign country in the world,” says William Wood, the American ambassador in Kabul. I ask if I may quote him on that. He hesitates, then says it’s all right, then adds: “It’s a ferociously foreign country.”

Mountainous, landlocked and remote, populated by legendary warriors - Pashtun, Tajik, Hazara and Uzbek - historically rich but economically dirt poor, it has been in a state of turmoil for almost 30 years, since the Soviet invasion of 1980.