British colonists arrived in the area where the park is in the late 19th century. At this time, the Athi plains east and south of what is today Nairobi had plentiful wildlife. Nomadic Maasai lived and herded their cattle among the wildlife. Kikuyu people farmed the forested highlands above Nairobi. As Nairobi grew—it had 14,000 residents by 1910—conflicts between humans and animals increased. Residents of the city carried guns at night to protect against lions. People complained that giraffes and zebras walked on and ruined their flower beds. Animals were gradually confined to the expansive plains to the west and south of Nairobi, and the colonial government set this area aside as a game reserve. Settlers from Nairobi including Isak Dinesen, author of "Out of Africa", rode horses among gazelles, impala, and zebras in this reserve.