Last month, Eliud Kipchoge finished a marathon in 1 hour, 59 minutes and 40 seconds — an audacious feat that no one had ever accomplished before. Kipchoge is from the Kenyan Rift Valley region. A day after he made history, Brigid Kosgei destroyed the women’s world record at the Chicago Marathon. She’s also from the Kenyan Rift Valley. East Africans — especially Kenyans and Ethiopians — have dominated marathons for decades, dashing across finish lines as their exhausted competitors barely made it. In the process, they’ve toppled their own records or those of their fellow citizens. And people are taking note — marathoners from all over the world go there to train before major races. Kenyan marathon runners are such a phenomenon that research organizations have done studies on why they dominate long distance races. And experts say it’s mixture of several things including location, the way of life and the environment.