Trade routes have developed since ancient times to transport goods from places of production to places of commerce. Scarce commodities that were only available in certain locations, such as salt or spices, were the biggest driver of trade networks, but once established, these roads also facilitated cultural exchange—including the spread of religion, ideas, knowledge, and sometimes even bacteria.

1. SILK ROAD // THE MOST FAMOUS TRADE ROUTE IN THE WORLD

The Silk Road is the most famous ancient trade route, linking the major ancient civilizations of China and the Roman Empire. Silk was traded from China to the Roman empire starting in the first century BCE, in exchange for wool, silver, and gold coming from Europe. Alongside spreading trade, the Silk Road also became a vital route for the spread of knowledge, technology, religion, and the arts, with many trading centers along the route—such as Samarkand in modern-day Uzbekistan—also becoming important centers of intellectual exchange.

The Silk Road originated in Xi’an in China and travelled alongside the Great Wall of China before crossing the Pamir Mountains into Afghanistan and on to the Levant, where goods were loaded on to ships destined for Mediterranean ports. It was rare for tradespeople to travel the full 4000 miles, and so most plied their trade on only sections of the route. As the Roman Empire crumbled in the fourth century CE, the Silk Road became unsafe and fell out of use until the 13th century, when it was revived under the Mongols. Italian explorer Marco Polo followed the Silk Road during the 13th century, becoming one of the first Europeans to visit China. But the famous route may have spread more than trade and cross-cultural links—some scientists think it was merchants traveling along the route who spread the plague bacteria which caused the Black Death.

2. SPICE ROUTE // BRINGING FLAVOR FROM EAST TO WEST

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Unlike most of the other trade routes in this list, the Spice Routes were maritime routes linking the East to the West. Pepper, cloves, cinnamon, and nutmeg were all hugely sought-after commodities in Europe, but before the 15th century access to trade with the East was controlled by North African and Arab middlemen, making such spices extremely costly and rare. With the dawning of the Age of Exploration (15th to 17th centuries), as new navigation technology made sailing long distances possible, Europeans took to the seas to forge direct trading relationships with Indonesia, China, and Japan. Some have argued that it was the spice trade that fueled the development of faster boats, encouraged the discovery of new lands, and fostered new diplomatic relationships between East and West (it was partly with spices in mind that Christopher Columbus set out in 1492 and ended up finding America).

The Dutch and English especially profited from the control of the spice trade in the East Indies—modern-day Indonesia, especially the area known as the Moluccas, or Spice Islands, which were the only source of nutmeg and cloves at that time. Wars were fought, lands colonized, and fortunes made on the back of the spice trade, making this trade route one of the most significant in terms of globalization.

3. INCENSE ROUTE // STARRING THE DOMESTICATED CAMEL

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The Incense Route developed to transport frankincense and myrrh, which are only found in the southern end of the Arabian Peninsula (modern Yemen and Oman). Frankincense and myrrh are both derived from tree sap that is dried in the sun; these nuggets of sap can then be burned as incense or used as perfume, and were also popular in burial rituals to aid embalming. The camel was domesticated around 1000 BCE and this development allowed the Arabians to begin to transport their valuable incense to the Mediterranean, an important trade hub. Frankincense and myrrh became a significant commodity for the Romans, Greeks, and Egyptians—indeed it was said that the Roman emperor Nero had a whole year’s harvest of frankincense burned at the funeral of his beloved mistress.

The trade flourished, and the overland route was, at its height, said to have seen 3000 tons of incense traded along its length every year. Roman historian Pliny the Elder wrote that it took 62 days to complete the route, although it is clear that at times the exact route shifted when greedy settlements pushed their luck and demanded taxes that were too high from the caravans coming through. By the first century CE, this ancient overland route was largely redundant, as improved boat design made sea routes more attractive.

4. AMBER ROAD // TRADING BEADS

Amber has been traded since c.3000 BCE, with archaeological evidence revealing amber beads from the Baltic having reached as far as Egypt. An Amber Road linking the Baltic with the rest of Europe was developed by the Romans, who valued the stone as both a decorative item and for medicinal purposes.

Large deposits of amber are found under the Baltic Sea, formed millions of years ago when forests covered the area. The amber washes ashore after storms, and can be harvested from the beaches across the Baltic, which is how many local amber traders built their business. However, during the crusades in the 12th and 13th centuries, the Baltic became an important source of income for the Teutonic Knights, who were granted control of the amber-producing region. The Knights persecuted the local Prussians brutally, and anyone attempting to harvest or sell amber was put to death. Today traces of the old Amber Road can be found in Poland, where one of the major routes is known as the “Amber Highway.”

5. TEA ROUTE // THE PRECIPITOUS TEA-HORSE ROAD

This ancient route winds precipitously for over 6000 miles, through the Hengduan Mountains—a major tea-producing area of China—through Tibet and on to India. The road also crosses numerous rivers, making it one of the most dangerous of the ancient trade routes. The main goods traveling the route were Chinese tea and Tibetan warhorses, with direct trades of tea-for-horses and vice versa being the main goal of merchants plying the route. Parts of the route were used starting c.1600 BCE, but the entire route began to be used for trade from about the seventh century CE, and large-scale trade was taking place starting in the Song dynasty (960–1279).

At least one piece of research suggests that in the period 960–1127 some 20,000 Tibetan warhorses were traded along the route every year in exchange for an eye-watering 8000 tons of tea. As sea routes became more popular, the significance of the road lessened, but during World War II it once again grew in importance as the Japanese blocked many seaports, and the Tea-Horse Road became an important route for supplies traveling between inland China and India.

6. SALT ROUTE // VIA SALARIA

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Salt has long been a precious commodity—it’s been used to flavor and preserve food, and as an antiseptic, for example. But easily harvested salt was a scarce mineral in antiquity, and so areas rich in salt became important trading centers. Routes connecting these centers to other settlements also became commonplace. Of the many such routes that sprang up, one of the most famous was the Roman Via Salaria (Salt Route), which ran from Ostia, near Rome, across Italy to the Adriatic coast. So precious was salt that it made up a portion of a Roman soldier’s pay, and it is from this that we get the word salary (from the Latin for salt, sal) and the phrase “Not worth his salt”—the latter because a soldier’s salt pay would be docked if he did not work hard.

Another important salt route across Europe was the Old Salt Road, which ran 62 miles from Lüneburg in northern Germany, which was one of the most plentiful salt sources in northern Europe, to Lübeck on the north German coast. During the Middle Ages this route became vital for providing salt for the fishing fleets that left Germany for Scandinavia, as the salt was used to preserve the precious herring catch. It would take a cart delivering salt some 20 days to traverse the Old Salt Road, and many towns along the way grew wealthy by levying taxes and duties on wagons as they passed through.

7. TRANS-SAHARAN TRADE ROUTE // TRADING ACROSS THE DESERT

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The Trans-Saharan Trade Route from North Africa to West Africa was actually made up of a number of routes, providing a criss-cross of trading links across the vast expanse of desert. These trade routes first emerged in the fourth century CE, and by the 11th century caravans made up of over a thousand camels would carry goods across the Sahara. Gold, slaves, salt, and cloth were the most important commodities on this route, but many other objects also found their way into the caravans, from ostrich feathers to European goods such as guns.

The trade route was instrumental in the spread of Islam from the Berbers in North Africa into West Africa, and with Islam came Arabic knowledge, education, and language. The Trans-Saharan trade route also encouraged the development of monetary systems and state-building, as local rulers saw the strategic value in bringing large swathes of land, and thus their commodities, under their control. By the 16th century, as Europeans began to see the value in African goods, the Trans-Saharan trade routes became overshadowed by the European-controlled trans-Atlantic trade, and the wealth moved from inland to coastal areas, making the perilous desert route less attractive.

8. TIN ROUTE // BRONZE AGE BUSINESS

The Tin Route was a major Bronze Age to Iron Age trade route that provided early settlements with access to a vital ingredient for metal-making—tin. Copper must be alloyed with tin to make bronze, an advance that occurred in the Near East around 2800 BCE and created a stronger, better metal than the type used previously. This new technology put tin much in demand, and as it is not found in many places, it became an important item for trade.

One such tin route flourished in the first millennium BCE from the tin mines in Cornwall in the far southwest of Britain, over the sea to France, and then down to Greece and beyond. Evidence for this route is provided by the many hillforts that sprung up along the way as trading posts. Historians believe that trade passed both ways up and down this route, as the hillforts provide evidence of exotic artifacts, including coral and gold. No written accounts survive from this period, but the archaeological record shows that technology and art traveled the route between northern Europe and the Mediterranean alongside tin—thus providing a vital link across Europe.