A dry sea

The largest desert in the world, the Sahara, is 3.5 million square miles of sand, rock, mountains, and plateaus stretching from the Nile River to the Atlantic Ocean. The whole of the United States would fit inside it.

But this inhospitable expanse—filled with waves of salt, stretching for miles in all directions, with a few small islands where fresh water and food make permanent settlement possible—seems more like a barrier, right? Describing the Sahara Desert is like describing an ocean. Many people who lived near the Sahara thought of it as a kind of sea. In fact, Sahel, the word for the transitional zone between the Sahara Desert and the savanna grasslands, comes from the Arabic word sāhil, meaning “shores.” How does our understanding of Earth’s largest desert change when we imagine it less a barrier and more as a navigable sea, linking people through the exchange of goods and ideas?

From 1200 to 1450, an extensive trans-Saharan trading system reached its peak. Huge caravans of camels and merchants transporting goods from one “shore” of the desert to the other. Beginning with the Arab conquests in the seventh century, trade across the Sahara linked the great kingdoms of West Africa to the Mediterranean and Indian Ocean worlds.

What would convince someone to try and cross the largest desert in the world? The same factors that would motivate someone to hop on a wooden boat and head out across the earth’s largest bodies of water. At its most basic, the development of extensive trans-Saharan trade routes required two things. First, it required trade goods valuable enough that people across the desert would pay for them. Second, merchants needed a cost-effective method of transportation to move those goods across the desert.

The ship of the desert

Like merchants at sea, caravans in the Sahara also faced storms and wrecks when desert winds forced them to abandon their wares or risk being stranded. Any successful caravan required experienced guides, and the best mariners in this dry sea were Berbers. Some Berbers were pastoralists who lived on the edges of the desert. Like pastoralists in Eurasia, the Berbers were essential to the growth of the trans-Saharan trade. They captained the “ship of the desert”—the camel.

Like the development of new ships and navigation techniques in the Indian Ocean, developments in travel technologies enabled new long-distance trade routes across the Sahara. The introduction of the camel was by far the most important of these. Camels are superior to horses for desert travel. Their wide toes are more suited to the terrain, and they can travel up to ten days without water. The Berbers improved the camel saddle, allowing them to carry even larger loads over greater distances. A single camel crossing the Sahara could carry around 400 pounds of trade goods. Over shorter distances, they could carry up to 1,200 pounds.

When you think of the Sahara, you probably picture camels. But the camels indigenous to North Africa went extinct during the Stone Age. Around 300 BCE, the dromedary camel (one hump) was reintroduced to North Africa. Scholars debate the timing and origin of this reintroduction, but once camels arrived, the Berbers quickly began using them to cross the desert.

Saharan caravans¹ were impressive feats of organization. In general, the merchants making their way north or south across the desert did not own camels; they often rented camels from pastoralists. Caravans set out during the cooler months from October to March, traveling at the coolest times of day. A caravan traveled around 20 miles a day, taking 70 days to cross the desert. The main routes followed water sources such as wells and oases.

Pastoralists in the Sahara were essential for the trans-Saharan trade, but they were also a threat to it. While friendly groups might act as trading partners and guides, others might attack smaller or undefended caravans. Rather than invade the desert, states and merchants paid tribute to pastoralists in order to ensure the safety of their caravans. By the thirteenth century, it was common for caravans crossing the Sahara to travel with 5,000-10,000 camels. Timbuktu, in the Mali Empire of West Africa, started out as a caravanserai, or a pitstop for caravans, before it grew into a center of learning and commerce.

A land of gold: The Mali and Songhai Empires

Many goods traveled along these trade networks, but it was the gold of West Africa and salt of the Sahara that drove the trade. Salt, which is necessary for human life, was in short supply in West Africa. Berber tribes controlled several salt mines, which allowed them to buy high-value goods like gold from merchants in West African cities like Jenne and Timbuktu. They could also purchase enslaved people in these cities. They transported everything and everyone back across the Sahara to cities like Sijilmasa (in present-day Morocco). From there, goods and enslaved people were taken to the Mediterranean and on to Egypt. The trans-Saharan routes reached their peak from the twelfth to fifteenth centuries, when a series of strong states in West and North Africa cooperated with the Berber tribes and asserted control over the trade.

The region of West Africa south of the Sahara was home to some of the continent’s most powerful empires and largest cities. Here, along the flood plains of the Niger River, agricultural societies like the Mali (1235–1670) and Songhai (1430–1591) empires thrived on sorghum, millet, and rice. These empires depended on trade across the desert to exchange their gold for salt and luxuries from the Mediterranean. The emperors of Mali and Songhai strictly controlled the movement of merchants across their land in an attempt to guard the secret locations of gold mines to the south. Their control of the trade routes enriched and expanded these empires.

Waves of change: The arrival of Islam

To the north of the Sahara, powerful Islamic empires and Muslim merchants united a vast swath of Afro-Eurasia from the Atlantic to the Pacific Ocean in a single trading system. As West Africans converted to Islam, this system expanded into the trans-Saharan trade.

Arab merchants made their way across the desert to trade salt, cloth, and other manufactured goods in exchange for gold in West Africa. West Africans also traveled north. A great many of these—as many as 9.3 million between 800 and 1800—were enslaved.² But plenty of West Africans made the journey voluntarily, many traveling on pilgrimage to Mecca.

Caravans and merchants carried abundant wealth, goods, and people across the Sahara. But perhaps the most important thing they carried weighed nothing at all: Islam. Islam was the most important factor in the expansion of trans-Saharan trade. After the Arab conquests of the seventh century, the Berbers converted to Islam. As trade expanded, many West African merchants converted as well. Islam provided a common language and value system, making communication easier. Written Arabic improved record-keeping in West-Africa. Arabic legal codes and written contracts increased trust between merchants.

In West Africa, Islam became the religion of urban elites. Since Islam spread by trade, it spread first to cities and to the wealthy. Most converts lived in market cities and were merchants or members of the ruling class. But most of the population was not urban, so local religions remained more important long after the arrival of Islam.

New routes

The combination of increased trade, cross-cultural exchange, and Islam ushered in a golden age for the empires of West Africa. Cities grew and flourished as centers of trade and learning. Timbuktu became a center of Islamic scholarship. Trade allowed travelers and scholars to move around the world, exchanging knowledge. Ibn Battuta, the famous Moroccan scholar who traveled from Morocco to China, also visited Mali and was impressed by its wealth and social structures. Mansa Musa, the ruler of Mali himself, made the Hajj to Mecca in the 1320s. He traveled with tens of thousands of camels and servants, carrying a fortune in gold. He spent so lavishly that he destabilized the Egyptian economy. His displays of wealth helped create myths that West Africa was a land where gold grew like plants in the ground.

Europeans began exploring the West African coast partly due to such myths. During the fifteenth century, Portuguese sailors moved further south, seeking a route around Africa to the Indian Ocean trade. They established new sea lanes bypassing the Saharan routes, making them less important to the global economy. But large caravans continued to cross the desert right up until the early twentieth century, when the first railroads and steamships reached the interior of West Africa.

1 A caravan is a group of people travelling together for protection, often for religious pilgrimage or trade. Caravans were common on the overland trade routes of Afro-Eurasia.
2 Slavery in this era had little to do with race or skin color. West African slaves were usually prisoners captured in war. White people from the Caucasus joined black people from East and West Africa in enslavement in the Mediterranean and Indian Ocean markets.