Just 34 years ago, archaeologists discovered the tomb of a princess who died in what is now the Chinese region of Inner Mongolia in 1018. The contents were intact, and they were astonishing. Both the princess and her husband were buried in wire-mesh bodysuits made of silver, with gold masks on their faces, and they were surrounded by a mass of luxury goods, as if they had dropped dead on the most lavish of shopping expeditions. But what was so impressive about these items was not just their quality, but their range of origins.

In addition to all the gold, silver and ceramic objects from China and Mongolia, there were pearls from the Indian Ocean, and carvings in rock crystal from Sumatra. Brass pots came from Iran, glass vessels were from Syria and Egypt, and chunks of amber had been brought more than 4,000 miles from the shores of the Baltic. So the whole tomb was testimony not only to the exquisite taste of the Liao dynasty, but also to huge networks of trade and travel.

Closer to the origins of those amber pieces is the island of Helgö, on a lake near Stockholm. Here archaeologists found a Viking hoard (from perhaps one or two centuries earlier) containing a baptismal water-ladle from Egypt, Arabic-inscribed coins and a bronze figurine of the Buddha, made somewhere in the Kashmir region. Thanks possibly to the commerce that passed through Constantinople, they had come into the hands of Vikings who raided and traded – and settled and ruled – in a vast area between the Baltic and the Black Sea.

Some of the details in these cases may be unusual (10th-century Sweden was not exactly buzzing with little Buddhas), but the larger patterns they point to can be matched in other parts of the world. As Valerie Hansen shows in this fascinating book, much of the inhabited globe already had complex systems of long-distance trade more than a millennium ago. Only one continent, Australia, seems to have missed the party altogether.

Africa was criss-crossed by trading routes, bringing two key commodities to the Mediterranean coast and the Muslim Middle East: gold and slaves. The city of Great Zimbabwe was rising, granite block by granite block; in its heyday it would produce a ton of gold per annum, and its rich traders would dine on green celadon plates from China. With cultural contacts came other influences too: the earliest surviving piece of writing in West Africa is an Islamic inscription from 1011, carved in Arabic at a commercial centre in Mali.