The Mexico City Olympics, held at roughly 2,240 metres, and the moment Kenyan distance running entered the world's attention.
Keino's Games
Kip Keino contested the 10000 metres, 5000 metres and 1500 metres.
In the 10000 he collapsed during the race with abdominal pain, later attributed to a gallbladder infection, resumed, and was disqualified for stepping off the track.
He won silver in the 5000 metres.
The 1500 final
Delayed by traffic, Keino ran part of the way to the stadium.
Ben Jipcho set a very fast early pace to break up the field. Keino took over and won in 3:34.9, beating world record holder Jim Ryun by around twenty metres, the largest winning margin in the event's Olympic history.
The Rift Valley
The concentration of elite runners is geographically narrow, centred on the highlands around Eldoret and Iten in the Rift Valley, at altitudes above 2,000 metres.
A dense network of training camps developed there from the 1980s onwards.
The explanations
Proposed factors include altitude adaptation, limb proportions favourable to running economy, high childhood activity levels including running to school, and strong economic incentives.
No single factor accounts for the pattern, and the combination has not been replicated elsewhere.
The record
Kenya has won more Olympic and world championship medals in middle and long distance running than any other country.
Why it goes on a wall
Because the sport treated altitude as a hazard to be survived, and a group of runners treated it as the ordinary condition of being alive.
Rift Valley spring.