A preliminary journey: AD 1261-1268

Two brothers, Niccolo and Matteo Polo, are Venetian merchants with interests in Constantinople and in Sudak, a Venetian colony on the coast of the Crimea. In 1261 they travel through the Black Sea to Sudak and then continue on to the Volga, where they visit Sarai berke, the capital city of the Golden horde. They stay among the Mongols for a year, but then find their route home blocked. Berke, the Muslim leader of the Golden horde, is at war with his cousin Hulagu, the pagan ruler of Persia.

The Polo brothers are advised that their wisest course is to continue eastwards to other Mongol centres along the old Silk road. They travel on to Bukhara, where they stay for two or three years.

In Bukhara they are eventually persuaded to move yet further east, to the greatest centre of Mongol power - the court of Kublai, the great khan, in China. Here the brothers are once again welcomed, and once again are enticed or coerced into spending a few years (it is impossible to leave a Mongol court without the khan's permission).

At last Kublai khan sends them home, with letters to deliver to the pope. They reach Venice in 1269. Niccolo's son Marco, only seven when he had last seen him, is now 15. Two years later the brothers set off again (they have promised Kublai khan that they will return, with precious commodities from the west). They take young Marco with them.

The road to Xanadu: AD 1271-1275

This time the journey east takes four years. The little party travels by sea from Venice to Syria, then rides or walks the rest of the journey - to Tabriz and by a southerly route, through Yazd and Kerman, before joining the Silk road to the north of the Hindu Kush. Eventually, after skirting the Gobi desert, they reach Kublai Khan's summer palace - the stately pleasure dome which he has built north of the Great Wall at Shang Tu, transliterated by Marco Polo into Italian as Ciandu and now widely known as Xanadu.

The Polo brothers receive a warm welcome from Kublai. They present to him young Marco - an encounter which, according to Marco, inspires immediate mutual admiration. Certainly Marco is offered employment.

Marco Polo in China: AD 1275-1292

Marco spends seventeen years in China, fulfilling a wide variety of tasks in Kublai Khan's administration. He is in effect a member of an occupying force, speaking Mongolian but not Chinese, so his understanding of the people is limited. But he travels a great deal, often trading on his own account as well as serving the emperor, and he describes many cities.

Hangzhou is his favourite. He pretends not to be certain which is more impressive - the number of its bridges or the number of its prostitutes. His interests seem more with the latter. Those who sample these women, he says (as if speaking of someone else), 'are so much taken with their sweetness and charms that they can never forget them'.

Marco has often been criticised for failing to mention one peculiarity of China - the drinking of Tea, which is already by this time a Chinese addiction. The two oddities which strike him most forcibly are a marvellous black stone, useless for building with, which the Chinese dig up and burn (one of the earliest references to coal); and their use of bank notes (see bank notes in China).

Paper money is not a Mongol innovation, being in use already in the Song dynasty, but Marco gives a fascinating description of government officials stamping the notes with a cinnabar seal.

The journey home: AD 1292-1295

Marco and his family prosper in the service of Kublai Khan, but eventually they become eager to leave. The khan is old. Chaos may follow his death, and they will be without a protector. Often they ask permission to go home. Always they are praised for their great contribution and told to stay - until luckily, in 1292, it suits Kublai to send them west. A young Mongol bride is to be sent to Kublai's great-nephew, the Il-khan ruling Persia.

The land route is at this particular moment blocked, by warfare between Mongol factions. A sea journey is considered safer. The Polo family, experienced travellers, may help to bring the bride to her destination.

The great khan orders Junks to be fitted out for the expedition. He gives the Italians messages of goodwill to be delivered to the pope and the kings of Spain, France and England. The party makes its way down through the China Sea, through the Straits of Malacca and up the west coast of India to the Persian Gulf. When they reach Tabriz, they find that Kublai's great-nephew has died. So the bride marries his great-great-nephew, the new Il-khan, instead.

After spending nine months with the court at Tabriz, the three Italians finally set off home. They reach Venice in 1295. Marco, now in his forties, has been away twenty-five years.

The Book of Marco Polo: AD 1298-1299

Marco has no intention of writing a book. Luckily for us he finds himself a prisoner in Genoa in 1298 (he has been in command of a Venetian galley in a war against the Genoese). A fellow captive is an author of romances, by the name of Rustichello. During a winter of enforced idleness, Marco tells him the story of his adventures. Rustichello writes it down.

The Book of Marco Polo, wherein is recounted the Wonders of the World becomes so popular that numerous manuscript copies of it are made in several languages.

Marco's contemporaries see his book primarily as what its title says - a book of wonders, rather than a factual account - and Rustichello's trade as a writer of romances has caused some more recently to question how much of the book is true, or whether Marco even made the journey to China.

But Chinese sources confirm many details which were unknown in the west in Marco's time. The most he can probably be accused of, in providing one of the world's greatest travel books, are two familiar failings - a selective memory and a story-teller's tendency to exaggerate. There is, however, no truth in the tradition that he brought back the secrets of Gunpowder, the Compass, Printing or noodles.