In San Francisco's early years, the area where AT&T Park now stands was part of San Francisco Bay. It is believed that sand from Rincon Hill (which anchors the western end of the Bay Bridge) and rubble from the 1906 earthquake was used as landfill to create the parcel in the late-19th century. The area was then used primarily for shipping and industrial uses. The Pacific Mail Steamship Company imported silk, tea, rice and opium from Asia to the United States to a dock at the foot of Brannan Street. The dominance of Asian commerce around the Brannan Street wharf led to the area being called China Basin. Just west of the ballpark site, the Southern Pacific Railroad built its headquarters (1867) next to the rail yards at Fourth and Townsend streets. In 1915 Southern Pacific opened a mission-style passenger terminal at Third and Townsend streets.