Why did Kenya surpass Ethiopia in middle and long distance running in recent years?

That's not true. Both countries are good at middle and long-distance running, but they are good at different men's events: 3000 and 3000-meter obstacles are Kenya's world; 5000, 10000 meters obstacle was monopolized by Egypt because of the existence of Bekkerel and Ethiopia's strong teamwork; Ethiopia has an absolute advantage, but the famous Dibaba does not participate in the competition, and his strength is greatly reduced. So some projects were taken away by Kenya.