A short history of Brentwood
Brentwood was home to the Julpuns who settled mainly in the upper corner of the East Bay. The Julpun were Native Americans who were a part of the Bay Miwok tribes who spoke the same language in an area, which is a branch of the Eastern Miwok Language. The Bay Miwok tribes would generally include 50–200 people in each village, where they would build their villages along the creeks since they were filled with fish. The Julpun believed that everything in the world had a life or spirit and were very in tune with the nature around them. They set things as sacred where they would pray at as part of their religious beliefs, they ended up coining Mt. Diablo, or as they call it Supremenenu, as the birthplace of the world. Due to this, they would hold the top points of Mt. Diablo to be used for sacred gatherings or religious purposes.
Back then the Julpun were never reached out to by ethnographers or linguists when the Julpun still retained their language, the Bay Miwok. They weren't mainly concentrated but spread out from the San Joaquin River to the bottom part of Marsh Creek which is now the southern part of Brentwood. Between 1806 and 1808 few of the Julpun migrated over to Mission San Jose with about 100 or so went by 1813. Later on Milliken listed down that about 141 Julpun members were baptized by 1819 from Mission San Jose. As time went on, Mission San Jose converted from religious beliefs and values to secular institutions where the Julpun members ended up leaving in 1836 back to their original territory. John Marsh ended up acquiring Rancho Los Meganos from Jose Noriega in 1837 which would cover modern Brentwood and back then cover the Julpuns territory. However, due to Mission San Jose revoking the spiritual possession it once had, the Julpuns may have gone back to their territory and ended up working under John Marsh on the land where their home once was.
In present time the Julpun tribe have more or less settled around the Bay Area. Some are living in specific groups, while others are living in society where they are preserving their native culture even though they may be away from their tribes. They (the Julpun) are working with the National Park Service, where they united under one federally recognized tribe called the Federated Indians of Graton Rancheria.
Adapted (trimmed) from the Wikipedia article Brentwood, California, revision 1380757862 by its contributors, licensed CC BY-SA 4.0.