Afghanistan, with its poppies, forbidding geography, earthquakes and internecine clashes, has been invaded since the fourth century. This history ends with the present invasion by Nato forces and explains the tensions between Russia, USA and Britain that led to it.

It took Alexander the Great six months to conquer Persia and three years to subdue Afghanistan, ‘a land of leonine and brave people’, he wrote to his mother, where ‘every foot of ground is like a wall of steel’. Two millennia on, it was Britain’s turn to take on the legendary warrior horsemen. In January 1842, three years after the start of the first Anglo-Afghan war (we’re now on the fourth), the beleaguered British garrison in Kabul, escorting 1,500 civilians, began the desperate retreat to Jalalabad. As they crossed the snows of the Hindu Kush, they were massacred by Pashtun tribesmen, leaving a single British survivor to tell the story. In 1979, 30,000 Soviet troops were dispatched to help Kabul’s new liberal government fight the Islamist mujahideen guerrillas, in whose ranks a youthful Osama bin Laden was already making a name. They retreated 10 years later with a butcher’s bill of 15,000 dead and 65,000 wounded, leaving behind a million dead Afghans. No country as ethnically, politically and religiously fragmented as Afghanistan, with its warlords, honour codes, Taliban fanatics, suicide bombers and a single illegal source of revenue – opium poppies – could expect an easy ride, but since the Soviet occupation it has not had a single year of peace. If only all guides to complex subjects were as clear, compact and impartial.