The geographer al-Bakri, writing before his death in 1094, described a fortress at Azougui "surrounded by 20,000 palms." He credited its construction to Yannu ibn Umar, brother of the two men who would lead the Almoravids out of obscurity: Yahya ibn Umar al-Lamtuni and Abu Bakr ibn Umar. The fort marked a frontier, a line in the sand between two Berber desert peoples of the Sanhaja confederation, the Lamtuna and the Gudala. They had been allies, veiled nomads who knew the routes between the wells. Then the alliance fractured. The Lamtuna held to the reformist movement that would become the Almoravids; the Gudala broke away. The split would soon be written in blood at a place just outside these walls.

In 1056, at nearby Tabfarilla, the Gudala fell upon the Lamtuna army based at Azougui and shattered it, killing its leader Yahya ibn Umar. It was the young movement's first serious defeat, and it might have ended there. Instead, the survivors regrouped under Abu Bakr ibn Umar and pressed on. Azougui and the battlefield beside it became revered ground for the Almoravids, a place of memory and resolve. Within a generation, armies that had nearly been broken in the dunes of the Adrar were marching on the Ghana Empire to the south and on Morocco to the north. By 1086 the Almoravids had crossed into Iberia and turned the tide of war between Muslim and Christian Spain.

Azougui was not only a fortress; it was a hinge of the trans-Saharan trade. The geographer al-Idrisi, writing in the twelfth century, put it plainly: "Whoever wants to go to the countries of Sila, Takrur and Ghana in the land of the Sudan cannot avoid this town." Caravans loaded with salt, dates, copper, and cloth passed through on the long crossing between Morocco and the goldlands of the south, where the Soninke people knew the place by another name, Quqadam. To control Azougui was to sit astride one of the great arteries of medieval commerce, where the wealth of the desert was measured in water as much as in gold.

The walls still trace the outline of the citadel, and the desert has preserved more than ruins. Rock carvings near the site reach back to the seventh century, older than the Almoravids by hundreds of years, a reminder that people watched these hills long before any empire claimed them. At the edge of the old town lies the cemetery and the mausoleum of al-Imam al-Hadrami, the scholar and judge who followed Abu Bakr ibn Umar here and served as qadi until his death in 1095. His tomb is plain, an unadorned stone structure in keeping with the austere faith he taught. It remains a place of pilgrimage and respect, and Azougui itself is on Mauritania's tentative list for UNESCO World Heritage recognition.