Wonder what’s different about Nigeria as far as lactose intolerance?
The African patch is Niger. Nigeria is it's southern neighbor.
Sorry for the nitpick.
The Fulani people of Niger raise cattle for milk, and have since ancient times. Milk, along with millet, is the mainstay of their diet. They ferment most of it, making ghee, etc.
But their cattle are poor producers of milk and the available forage is not very good for milk production either.