Prosperity at a chokepoint invites company, not all of it welcome. Oral traditions disagree on who founded the trading town, whether Marka merchants from Dia or Dyula traders from Djenné, but they agree it grew rich. Riches drew armies. In 1542 the Songhai ruler Askia Ishaq I attacked the place. In 1690 Biton Coulibaly seized it for the rising Bamana Empire. In 1739 Famaghan Ouattara of the Kong Empire, intervening in a Bamana civil war, destroyed the town entirely; it was rebuilt a little to the north, as towns at valuable crossings always are. Each conqueror wanted the same thing: the road, the river, and the taxes that flowed across both.

In the 1830s the preacher Cheikhou Amadou folded San into the Massina Empire, a strict theocratic state governed by Islamic law. That allegiance saved the city. When the warrior-scholar El-Hajj Omar Tall swept through and shattered Massina in the 1860s, leaving destruction across the region, he spared San. The town that had been sacked and rebuilt so many times survived this round not by its walls but by its prayers. There is a lesson in San's long history about which kind of strength endures: the fortifications fell, but the marketplace and the faith kept returning.

San still trades for a living. Highways cross here as the river once did, carrying goods through a town that has never forgotten how to sell. It is a center for bogolanfini, the mud cloth for which Mali is famous, woven in narrow strips and dyed with fermented river mud and plant tannins, each ochre and indigo pattern carrying meaning older than any of the empires that fought over the crossing. Horses are bred here, and rice grows green in the floodplain along the Bani. The dry season bakes the streets from October to May; then the rains come, the river rises, and the delta does what it has always done, which is feed the people who learned to live at its edge. San is also the birthplace of Bah Ndaw, born here in 1950, who would briefly serve as president of Mali.