In Zegoua, a town in southeastern Mali, I stand on the patio of my hotel where the border — between Mali, a country at peace, and Cote d’Ivoire, divided by war — bumps the concrete. I am the lone guest in this two-story, white-washed building with a top floor that resembles the bridge on a steamboat. The flags of Burkina Faso, Mali, Cote d’Ivoire, and France hang above the hotel entrance, stuck in the heat.

A Malian named Hamidou Sakara, who runs the hotel, and I are listening to a call-in trivia show on Radio Bamako, broadcast from the capital city. The program’s topic is African geography. The host tosses out a question. “What physical feature marks Mali’s border with Senegal?”

“It’s the Faleme River,” Hamidou says.

A man calls with the same answer.

“Well,” says the host, “the River Faleme forms nearly the entire border with Senegal, but a… More…