Merv, the Silk Road city that was once among the largest in the world

Merv lies in the oasis of the Murghab River, in the south of Turkmenistan, where a river flowing down from the mountains of Afghanistan fans out and disappears into the sands of the Karakum desert. For more than two thousand years, the oasis supported a great city, a crossroads on the trade routes between Persia, Central Asia, India and China. It was ruled in turn by Persian kings, by the successors of Alexander the Great, by the Parthians and the Sasanians, and by the Arab caliphs. Under the Seljuk Turks, in the eleventh and twelfth centuries, it was one of the great cities of the Islamic world, a capital with libraries, observatories and scholars.

Today the site is a vast, eroded landscape of mud-brick walls, mounds and ruins spread across many square kilometres of desert, near the modern town of Mary. It is a World Heritage Site and one of the most evocative places in Central Asia.

A city that kept moving

What makes Merv unusual is that the city moved over time, building a new city beside the old one rather than on top of it. As a result, the remains of several cities lie side by side, each from a different period. Erk Kala, the oldest, is a high, round fortress mound dating back to the Achaemenid Persian empire, around two and a half thousand years ago. Beside it, Gyaur Kala is a great square walled city of the Hellenistic and Sasanian periods. To the west, Sultan Kala was the vast Seljuk capital, enclosed by massive walls. Later still, after the Mongol destruction, the Timurids built a smaller town nearby.

At its height in the twelfth century, under the Seljuk sultan Sanjar, Merv was one of the largest cities in the world, by some estimates perhaps the largest of all.

The Mongols, and what survived

In 1221 the Mongol army, led by a son of Genghis Khan, besieged Merv. The city surrendered, but its inhabitants were massacred almost to a person, according to the chroniclers, who gave enormous numbers of dead that historians treat with caution. Merv never fully recovered. Its irrigation system was wrecked, and though a smaller town grew up again, the great city was gone.

Some remarkable buildings survived. The mausoleum of Sultan Sanjar, built in the middle of the twelfth century, is a massive cube of brick crowned by a great dome, once covered in turquoise tiles, rising above the ruins of the Seljuk city. It is one of the great monuments of early Islamic architecture. Nearby, the two Kyz Kalas, the Greater and Lesser, are strange, fortified mansions with walls of corrugated mud brick, like giant folded curtains, built in the early medieval period.

Merv also played a part in the history of the Islamic world. It was from Merv, in 747, that Abu Muslim launched the revolt that overthrew the Umayyad caliphs and brought the Abbasids to power. Early in the ninth century, the caliph al-Ma'mun ruled from Merv for several years before moving to Baghdad. In the Seljuk period, the city's libraries were among the richest anywhere, and scholars travelled from far away to use them.

Nisa, and the tours

Near Ashgabat, the capital, the ruins of Nisa were one of the early royal centres of the Parthian empire, which rivalled Rome in the east. Its excavations have produced fine ivory drinking horns and sculptures. It too is a World Heritage Site.

Explore Worldwide's Silk Road Highlights: Uzbekistan and Turkmenistan, twelve nights in May, June and September, includes Merv and the modern town of Mary, Ashgabat and Nisa in Turkmenistan, and Bukhara, Khiva, Samarkand and Tashkent in Uzbekistan.

Explore Worldwide's The Five Stans of the Silk Road, twenty nights, includes Ashgabat and Nisa in Turkmenistan, along with Kunya-Urgench, the old capital of Khorezm in the north of the country, and the cities of Uzbekistan, Tajikistan, Kyrgyzstan and Kazakhstan. Merv is not among its listed places, so it is worth checking the itinerary if the city matters to you.

Turkmenistan requires a visa, which can be difficult to obtain, and an organised tour is usually the simplest way to visit. Spring and autumn are the best seasons, as summer in the Karakum desert is extremely hot.