For most of its thousand-year run, the wealth of Kanem and then Borno did not come from farming the Chadian sahel — it came from sitting astride one of the busiest arteries of the medieval world. The trans-Saharan caravan routes from Tripoli and Fezzan crossed the desert and emerged at Kawar and Bilma, where the salt mines of Bilma supplied the entire central Sudan; from there the road ran south-west to Birni N'gazargamu, the imperial capital of Borno from 1472 to 1808. Along it moved salt, copper from Takedda, horses, brassware, Egyptian cottons, Indian silks and finished steel weaponry inbound; ivory, ostrich feathers, hides, gum arabic, kola from the Volta, and — above all — enslaved people outbound.
The Kanem–Borno tax base was the *jangali* (cattle tax) on the nomadic Kanembu and the *kasar sarki* (royal revenue) on the caravan trade. The Mai (king) was paid in horses and chain-mail armour, in *lifidi* (quilted horse-armour), and in the literacy of the *ulama* class he financed. Foreign trade — not subsistence agriculture — paid for the army, paid for the embassies to Tripoli, Fez, Cairo and Constantinople, and paid for the Islamic scholarship that made Borno the senior centre of learning between the Senegal and the Nile.
The empire's economic peak under Mai Idris Alooma (r. c.1564–1596) coincided with diplomatic missions to the Ottomans and the import of Turkish-trained musketeers — the first systematic introduction of firearms south of the Sahara. The decline tracked the slow rerouting of trans-Saharan trade in the 18th century toward the Atlantic coast, accelerated by the Sokoto jihad which severed Borno from the Hausa cities, and ended at the destruction of the empire by Rabih az-Zubayr in 1893.