The story really begins in 1960. An Ethiopian runner called Abebe Bikila lined up at the Olympic marathon in Rome - and noticed that his shoes were uncomfortable. So he took them off. He ran the entire 42 km race barefoot, on the cobblestones of an Italian city, and won the gold medal. He was the first ever African athlete to win Olympic gold.
Four years later, at the next Olympics in Tokyo, Abebe Bikila did it again - this time with shoes on, and just a few weeks after having his appendix taken out. Two Olympic marathon gold medals, four years apart.
Since then, Ethiopia has kept producing world-class runners. Haile Gebrselassie set 27 different world records in his career and is sometimes called the greatest distance runner of all time. Tirunesh Dibaba, Kenenisa Bekele, Tigist Assefa - all Ethiopian, all gold-medal winners.
Why so many champions from one country? Scientists think there are several reasons. Many top runners come from the Ethiopian highlands, where the air is thin so the body learns to use oxygen brilliantly. Lots of children run several kilometres to school every day from a young age. And there is a strong culture of training in groups, pushing each other on. Running matters in Ethiopia.