The first inhabitants of Round Valley were the Yuki, who lived there for thousands of years in harmony with their natural surroundings. In 1854, European settlers entered the valley. In 1856, conflicts between settlers and Yuki escalated, and to protect local tribes the entire watershed was designated a reservation. Additional tribes were subsequently forced onto the property: Nomlacki, Wylaki, Lassik, Sinkyone, Pomo, including Cahto, Kabyeo, Shodakai, Yokayo, Shokawa, Shanel, and Kashaya and Habenapo among others, Wappo, Concow Maidu, Colusa, and Achumawi. In 1864, the government reduced the reservation by four-fifths to its current size.