Ghana lay in the Sahel, the dry transitional country spread across what is now southeastern Mauritania and western Mali. It was a kingdom built on geography. To the south lay the goldfields of Bambuk and beyond; to the north, across the Sahara, lay the salt mines and the markets of the Mediterranean world that craved African gold to mint their coins. Ghana controlled neither resource directly. What it controlled was the crossing. By the time Muslim merchants first led their camel caravans across the desert in the centuries after the 7th, Ghana was already the most powerful state in the Sahel - a clearinghouse for a trade that linked West Africa to Cairo, Cordoba, and Baghdad. The word that reached the Arab world for this place was simple and exact: the land of gold.

Most of what we know comes from al-Bakri, a Moorish scholar in Muslim Spain who never set foot in Ghana but questioned the merchants who had. Writing around 1068, he described a court of deliberate splendor. The king held audience surrounded by pages holding gold-mounted swords; in the domed pavilion where appeals were heard stood ten horses draped in gold-embroidered cloth. Even the dogs that guarded the royal door wore collars of gold and silver. This was not vanity alone - it was statecraft, a display of wealth meant to overwhelm the visitor and announce the reach of the throne. Kingship passed through the female line, traditionally to the son of the king's sister, a matrilineal succession that struck the Arab chroniclers as strange and worth recording. Ibn Hawqal, writing in the 970s, simply called the king of Ghana the wealthiest ruler on the face of the earth.

Long before the Arab geographers, the Soninke people who built Wagadu told its origins in story. A man named Dinga, the traditions say, came from the east, and to take power he had to kill a serpent deity and marry its daughters, who became the ancestors of the ruling clans. In many versions a protective serpent, Bida, watched over the kingdom in exchange for a yearly sacrifice - a maiden given, and in some tellings rain and gold returned. Pythons live in the wet grasslands and vanish in the dry season, and it is easy to see how a serpent came to stand for the rains that made the Sahel livable. The legend of Wagadu's founding, and of its fall, runs deep in Soninke memory still, a fragment of what was once a far longer epic now lost to time.

The trade that fed the empire was a near-perfect exchange of opposites. Salt came south from the Sahara, scarce and essential in the tropics; gold went north, abundant in the goldfields and prized everywhere beyond them. Al-Bakri recorded the tax precisely: one gold dinar levied on each donkey-load of salt brought in, two on each load carried out, with fixed dues on copper and other goods besides. Ibn Hawqal once saw a cheque - a written promissory note - for 42,000 dinars, a sign of how sophisticated this commerce had become. Iron, ivory, textiles, and leather moved through the markets too; much of the fine worked leather later sold in Morocco began here. The empire grew not by mining wealth but by standing in its path and taking a cut of every crossing.

No single catastrophe ended Ghana. Older accounts blamed a conquest by the Almoravids, the veiled Berber movement of the western Sahara, but modern scholars are skeptical - the archaeology shows no sudden destruction, and contemporary writers describe the Almoravids as merely bordering Ghana, not crushing it. What is clear is that around 1076 the empire converted to Islam, and that over the following two centuries its grip on the gold trade slipped toward rising rivals. In its final centuries Ghana leaned increasingly on slave raiding and trading to survive, a grim measure of how far the old prosperity had ebbed. By 1203 the Sosso had seized control, and after the Battle of Kirina the city that had been Ghana's heart became a junior ally of the new Mali Empire. The capital was abandoned sometime in the 15th century. But the name endured: in 1957, when the British Gold Coast won independence, it took the name Ghana - reaching back across a thousand years and a thousand kilometers to the first great empire of the Sahel.