April 15th, 2015 | 6:00am

Photo by author

My first day in Bukit Tinggi, a town in the rain forest-swathed mountains of West Sumatra—a region home to the Minangkabau ethnic group, the world’s largest matrilineal society—I swore I heard a woman calling the Muslim midday prayer broadcasting from a white mosque.

In my confusion I stopped and looked around, as if the townscape—narrow streets lined with wooden buildings whose roof-lines curve into distinctive bull horn-like tips, with tropical gardens in flower—would somehow reveal the muezzin. The clear, mid-range voice sounded feminine, a little breathless, as if the singer had rushed to make it on time. I pictured a young woman wearing a brightly colored hijab...