Umar Tall was no ordinary refugee. He had made the pilgrimage to Mecca, earning the title El Hadj, and returned steeped in the Tijaniyya Sufi order, which he would spread across the region. When he settled at Dinguiraye, he set engineers to work. Samba Ndiaye and a man remembered as "Johnny" Bambara directed the construction of the town and its tata, a thick-walled earthen fortress of the kind that dotted the Sahel. The site was shrewdly chosen. Caravans moved through here along trade routes linking the Niger River to the Atlantic coast, with traffic running steadily down to Freetown. A holy city that controlled commerce could fund a holy war.

The local king, Dyimba Sako, watched his new neighbor's power grow and grew alarmed. He attacked Dinguiraye, and he lost. That defeat became a beginning rather than an end. In 1852, Umar Tall declared a full-scale jihad against the animist states and the Muslims he judged to have lapsed, organizing his followers into a disciplined army equipped, in part, with imported firearms. On the 21st of May, 1854, he rode out from Dinguiraye to campaign in the north. He never came back. Over the following years his armies pushed across the upper Senegal and into what is now Mali, building an empire that would stretch for hundreds of miles, while the holy city he left behind held its place in the imperial imagination.

Command of Dinguiraye passed to Umar Tall's son Habibou. When Umar died in 1864, his son Ahmadu inherited the wider empire. But the succession bred fracture. Habibou joined a rebellion in 1868 and was captured and imprisoned. Ahmadu's cousin Saidou took over at Dinguiraye and was killed in battle in 1876. By the close of the decade, Aguibou Tall had arrived to govern. Cut off from the rest of the Toucouleur realm and pressed on every side, Aguibou turned to the advancing French for protection, an alliance that would cost his family its independence. In May 1891, Dinguiraye was annexed to the French colonial empire. When the French exiled the last local leader, Makki, in 1899, even the town's nominal autonomy came to an end.

For all the wars launched from here, what most visitors remember is the mosque. Until recent decades its great roof was thatched, a vast dome of woven plant fiber rising above the earthen walls, an architecture that belonged wholly to the Sahel rather than to any imported style. The mosque remains the heart of Dinguiraye, a place of pilgrimage for followers of the Tijaniyya order who come to honor the founder's memory. The town that grew up around it now holds tens of thousands of people, its market and faith carrying on long after the empire dissolved. History launched its campaigns from Dinguiraye and then receded, but the call to prayer never stopped.