Local people are mostly of the Keiyo tribe.
Many famous Kenyan runners come from the district, including Saif Saaeed Shaheen (born Stephen Cherono), Vivian Cheruiyot and Lornah Kiplagat.
The world record marathon holder, Kelvin Kiptum, was also from the region.
The area is used by local and foreign athletes for high-altitude training.
Mining of fluorite by the Kenya Fluorspar Company is the largest industry in the former district.