Don Francisco de Coronado was known to have explored the area and camped near present-day Bernalillo around 1540. However there is evidence that people occupied the area several thousands of years ago. Sandoval county was part of Santa Ana County around 1852 and then around 1903 became a separate county. Part of the county was lost around 1949 to form Los Alamos county. Sandoval county is home to nine Indian pueblos, three Navajo Chapters and part of the Jicarilla Apache Reservation. There are four hot springs areas in this county; Spence Hot Springs, San Antonio Hot Springs, McCauley Warm Springs and Soda Dam and Springs all located in the Jemez mountains. An interesting spot to visit is the Jemez State Monument where you will find the prehistoric site of the Pueblo of Giusewa and the early 17th century ruins of the mission Church of San Jose de los Jemez. Although only ruins and a bell tower remain; visitors can walk through the excavated mission ruins and see the construction of six-to eight-foot thick walls.