The Kikuyu(also Agĩkũyũ/Gĩkũyũ ) are a Bantu ethnic group native to Central Kenya. At a population of 8,148,668 as of 2019, they account for 17.13% of the total population of Kenya, making them Kenya's largest ethnic group. Gĩkũyũ is derived from the word mũkũyũ which means sycamore fig ( mũkũyũ ) tree". Hence Agĩkũyũ in the Kikuyu language translates to "Offspring of The Big Sycamore". The alternative name Nyũmba ya Mũmbi , which encompasses Embu , Gikuyu , and Meru , translates to "House of the Potter" (or "Creator").

The Agĩkũyũ nation was divided into nine clans. Each clan traced its lineage to a single female ancestor and a daughter of Mumbi. The clans were not restricted to any particular geographical area, they lived side by side. Some clans had a recognized leader, others did not. However, in either case, real political power was exercised by the ruling council of elders for each clan. Each clan then forwarded the leader of its council to the apex council of elders for the whole community. The overall council of elders representing all the clans was then led by a headman or the nation's spokesman.

Ngai or Mwene-Nyaga is the Supreme Creator and giver of all things. He created the first Gĩkũyũ communities, and provided them with all the resources necessary for life: land, rain, plants, and animals. Ngai cannot be seen but is manifested in the sun, moon, stars, comets and meteors, thunder and lightning, rain, rainbows, and in the great fig trees (Mugumo). These trees served as places of worship and sacrifice and marked the spot at Mũkũrũe wa Gathanga where Gĩkũyũ and Mũmbi – the ancestors of the Gĩkũyũ in the oral legend – first settled. Ngai has human characteristics, and although some say that he lives in the sky or in the clouds, Gĩkũyũ lore also says that Ngai comes to earth from time to time to inspect it, bestow blessings, and mete out punishment. When he comes, Ngai rests on Mount Kenya (Kīrīnyaga) and Kilimambogo (kĩrĩma kĩa njahĩ). Thunder is interpreted to be the movement of Ngai and lightning is the weapon used by Ngai to clear the way when moving from one sacred place to another. Some people believe that Ngai's abode is on Mount Kenya. In one legend Ngai made the mountain his resting place while on an inspection tour of earth. Ngai then took the first man, Gikuyu, to the top to point out the beauty of the land he was giving him.