San Martín de Chacas is a Peruvian town, capital of the eponymous district and the Asunción Province, located in the east-central region of Ancash. It has an urban population of 2,082 located at 3,359 meters; and a district of 5,334 people. The district, located in the sub-basin of the Marañon River, has an area of 447.69 km², which represents 85% of the province.