The Suisun, or Suisunes, were a Patwin band of Wintun people. They lived in the Suisun Bay and Suisun Marsh regions of Solano County in Northern California.
Their traditional homelands stretched between what is now Suisun City, Vacaville and Putah Creek around 200 years ago. The Suisun's main village, Yulyul, is believed to be where Rockville, California, is today.
Suisun Bay (/səˈsuːn/ sə-SOON; Wintun for "where the west wind blows") is a shallow tidal estuary (a northeastern extension of the San Francisco Bay) in Northern California. It lies at the confluence of the Sacramento River and San Joaquin River, forming the entrance to the Sacramento–San Joaquin River Delta, an inverted river delta. To the west, Suisun Bay is drained by the Carquinez Strait, which connects to San Pablo Bay, a northern extension of San Francisco Bay. Grizzly Bay forms a northern extension of Suisun Bay. Suisun Bay is between Contra Costa County to the south and Solano County to the north.
The bay was named in 1811 after the Suisunes, a Patwin tribe of Wintun people.