Deep in Burma's irrawaddy delta, the rhythms of Kyonku village echo from another century. Oxen and buffalo plow the paddies; women in sarongs smoke pipes and swat mosquitoes, which can carry malaria or dengue. Decades ago, ethnic Karen insurgents, one of many tribal militias that battled Burma's long-ruling military regime, prowled the hills. Today the Karen rebels have laid down their arms. Instead, wild elephants roam after sunset, occasionally charging villagers in a fury of tusks.
The wooden house in Kyonku where Burma's 67-year-old President, Thein Sein, grew up still stands, a creaky time capsule in a country largely preserved in...