More than two millennia ago, a sophisticated irrigation system channelled meltwater from the Pamirs into the Amu Darya (Oxus) Delta, a region known as the Khorezm, transforming the desert into a fertile oasis of lakes, reed beds, marshes and lush farmland. The lynchpins of this long lost civilization were a chain of mud-walled citadels, whose remains now rise from low sand hills, an hour’s drive north of Urgench. Almost entirely forgotten but spellbindingly beautiful, two of the most spectacular are Toprak Kala and Ayaz Kala. Both may be visited on day trips from Khiva, or explored at greater leisure by staying in a nomads’ yurt camp nearby – worth a night under camel hide to see the fabulously starry skies of the Kyzylkum at night, and the spectacle of the forts glowing red in the dawn sunshine.