When Timothy Cheruiyot won the 1,500 metres at the World Athletics Championships in 2019 and 2022, he extended a tradition of Kenyan middle-distance excellence that had begun with Kip Keino in 1968. Like most of Kenya's great runners, Cheruiyot came from the Rift Valley, trained at altitude and combined natural talent with ferocious work ethic. The concentration of athletic talent in this relatively small region of Kenya, where thin air and decades of running culture have produced generation after generation of champions, remains one of the most extraordinary phenomena in sports.