Empires of the Indus, By Alice Albinia

A river runs through this journey of discovery about Pakistan's history

How little we know about Pakistan. For a country at the troubled centre of geo-politics, with a population greater than Russia's, the general perception gets not much further than "hard-line military state, with attitude". So this bid to trace Pakistan's great river, the Indus, from mouth to source, is all the more welcome for its erudition. With a background at SOAS in London, Alice Albinia is well placed to unpick the country's complex history in this impressive debut.

One oddity about Pakistan, given its rivalry with India, is that so much of the Indian cultural heartland should lie within its borders. The Rig-Veda is set there and "the demonised neighbour is actually Hinduism's motherland", containing the river that gives India its name. Alexander the Great famously reached the Indus at the end of his epic eastern campaign, a story Albinia tells with verve and erudition, and did so just as Buddhism reached the area. As a result, statues of Buddha in Swat and Gandhara have a Grecian poise: "Greek and Indian art-forms, languages and social structures commingled like rivers for a brief and mutually sympathetic moment."

Taxila went on to flourish as an ecumenical university under Indo-Greek rulers such as Menander. For centuries, the upper valleys of modern Pakistan that now swarm with fundamentalists were a byword for religious tolerance. Yet Albinia also deconstructs Alexander's mythologising. Far from his Indian campaign being the greatest exploit of an audacious journey, it made so little military impression that not one local historian bothered to record it; the territory was swiftly reconquered. Only in Greece was it turned into legend.

Albinia's intrepid journey to the river's source is at times an extremely long walk to the Hindu Kush. She also follows John Simpson and just about every other journalist by slipping into Afghanistan disguised in a burqa; guards must sigh wearily as yet another foreigner approaches.

But the sense of a country continuously reinventing itself is luminous. There is a sad epilogue about the destruction of perhaps the last monumental stone Buddha in Swat, dynamited just last year by fundamentalists. Before then, the statue was seen only by the local shepherds, a glimpse of the valley "when the kings were Buddhist, when caravans of silk passed through...and when Chinese monks braved the dragons and sorcerers of the Indus".