Most of the world's fastest runners come from a single tribe in Kenya, Africa, called the "Kalenjins."
The Kalenjin are an ethnolinguistic group indigenous to Kenya, residing mainly in what was formerly the Rift Valley Province. They are estimated to number a little over 4.9 million individuals as per the Kenyan 2009 census and are divided into the Kipsigis, Nandi, Keiyo, Marakwet, Sabaot, Pokots, Tugen, Terik, and Ogiek. They speak the Kalenjin language, which belongs to the Nilotic group within the wider Nilo-Saharan family.
The Kalenjin have been called by some "the running tribe." Since the mid-1960s, Kenyan men have earned the largest share of major honors in international athletics at distances from 800 meters to the marathon; the vast majority of these Kenyan running stars have been Kalenjin. From 1980 on, about 40% of the top honors available to men in international athletics at these distances (Olympic medals, World Championships medals, and World Cross Country Championships honors) have been earned by Kalenjin.