History
The name of the district comes from the town of Olmos, which means "elms." This is because the light-colored bark of the trees in the nearby forest reminded Spanish settlers of the elm trees in Spain. When the Spanish arrived, the area was home to the Quechua people. The large region of Olmos was part of the Kingdom of Copiz, which was under the Inca Empire. The existing town was officially recognized in 1544 by the viceroy Blasco Núñez Vela.
Hydrographics
The main river in the district is the Olmos River. Other important rivers include the Cascajal River, the Insculás River, the Ñaupe River, and the San Cristóbal River. The Limón Dam is part of the Olmos irrigation project. This project aims to water dry areas west of the Andes by building a dam on the Huancabamba River, which often floods.