Koitalel Arap Samoei was the most important of the 'orkoiyot', i.e. the spiritual and political leaders of the Nandi main tribe of the Kalenjin ethnic group in north-western Kenya. According to the Nandi, the orkoiyot was chosen through signs from Asis, or God, to carry messages to his people.
Born around 1860 in the village of Samitu, he was the last of the four sons of the orkoiyot Kimnyole and was considered by his father to be the most talented in magical practices and divinatory skills among his brothers.

At the age of twenty-five, Samoei succeeded his father as Orkoiyot, the s. Orkoiyot traditionally came from the Talai clan of the Nandi, who were believed to have been chosen by Asis (God) to carry messages to the people.

A few years after his appointment, Koitalel prophesied the arrival of a fire-breathing black snake that would pass through the land of the Nandi.
Not long afterwards, the British colonisers expressed to the Nandi chief their intention to build a railway from Mombasa to Kampala, Uganda, that would cross the Nandi lands. Koitalel strongly opposed this and a war ensued that lasted about 20 years, until the death of the orkoiyot in 1905.

It was one of the first and fiercest resistance by the Kenyan people, because the Nandi have always been considered among the best fighters in East Africa.
Koitalel arap Samoei was a strategist capable of planning ever changing attacks on the railway workers and ambushing the British when they least expected it.

His men repeatedly stole the construction materials of the 'Lunatic Express' and used them to make weapons and battle ornaments.
In 1905, even though the railway was practically completed, the British decided to come to terms with the Nandi chief and organised a peace meeting. The agreement was that each of the two sides would come to the meeting with five trustworthy men.

In reality, the 'King's African Rifles', led by Colonel Richard Meinertzhagen, were backed by 75 other armed men, hiding in the forest, who at the right moment, just as the orkoiyot approached the colonel to shake his hand, came out and killed him along with four of his men. The episode was recounted by the only Nandi eyewitness who escaped the ambush. According to the Nandi community, Meinertzhagen beheaded Koitalel in front of his soldiers and a few years later transported the skull to England.

Having lost their greatest orkoiyot, the Nandi could no longer fight. This marked the end of the Nandi resistance. The construction of the railway continued uninterruptedly through the Nandi territory.
After Kenya's independence, a museum was built in the Nandi Hills to commemorate Koitalel Arap Samoei and his commitment to the freedom of his people.