The Keiyo (also known as Elgeyo) are an ethnic group that is part the larger Kalenjin ethnic group of Nilotic origin. Currently they live near Eldoret, Kenya in the highlands of the former Keiyo District now part of the larger Elgeyo Marakwet County. The Elgeyo originally settled at the foot hills of elgeyo escapement. The area between kerio river to the east and escapment to the west. Due to drought and famine at the valley, the keiyos started to climb the escapment and started to settle on the highland east of uasin gishu plateau. When the british came, the keiyos where pushed to settle in cluster which was called reserves. The Keiyo subsist mainly on grain, milk, blood and meat provided by their cattle, sheep and goats.
The name Keiyo or Elgeyo have been used interchangeably. The former name being disputed as a corruption of the latter true name which was coined by the Uasin Gishu Maasai who were the neighbors of the Keiyo in the mid 19th century at the western side of expansive Uasin Gishu plains.
The Keiyo like the rest of the Kalenjin originated from a country in the north known as Emetab Burgei, which means, the hot country. The people are said to have traveled southwards passing through Mount Elgon or Tulwetab Kony in Kalenjin. The Sebeii settled around the slopes of the mountain while the others travelled on in search of better land. The Keiyo and Marakwet settled in present Uasin Gishu plateau, Kerio Valley and Cherangani Hills. The arrival of Warring Uasin Gishu Maasai in the present day Uasin Gishu plateau forced the Elgeyo to move away into the present day Kerio Valley during the expansion of the tribe. The loss of much of their grazing lands forced them to reduce their herds and rely more on agriculture.
Elgeiyo people speak a Kalenjin/Kutiit language that falls under the Kipsigis - Nandi - Keiyo - Southern Tugen - Cherang'any' cluster.
There are three predominant sub dialects of Keiyo dialect. These are Irong, Mutei and Metkei.
Territorially, the Elgeiyo People divided their land into 16-east-west stretches to control intermarriage and displacement of a clan by other clans and a system of totems were acquired. The land was divided so that each group had access to the banks of Kerio River and thus the totems ran perpendicular to the river. From the south to the north the clans are Metkei, Kapkwoni, Maoi, Tumeiyo, Kowochi, Mwen, Sego, Chebior, Chang'ach, Rokocho, Mutei, Maam, Irong', Kaptany and Kapchemutwa. The land was sub-divided to members of the same clan marked by a series of stones referred to as Koiwek.
The Elgeiyo social organisation centres on the age set, or ebendo. There are eight age-sets (ebenwek) which are rotational, meaning after the end of one age set (after approximately 120 years), new members of age-set are born. Unlike the Nandi and the Tugen who have only seven age sets (due to loss of an entire age set in battle), the Keiyo retained all the eight age sets. The order is given below. Ebendo was given out during initiation. The age set system is organized in such a way that a father and a son cannot be of the same or sequential age sets. That is, there ought to be one ebendo between a father and a son. For example, a Kipkoimet cannot beget a Kaplelach. The Elgeiyo do not consider a woman to have an age set, hence she can marry any age set except that in which her father belongs.
Due to population growth over time, the Keiyo community gradually moved and settled in urban areas to do business in major urban centers including Eldoret town where they are now actively engaged in businesses alongside the Marakwets, Nandis and other non-Kalenjins.