Silicon Valley is about a mature company.
  Historically, the term Silicon Valley was treated as synonymous with Santa Clara Valley, and then its meaning later evolved to refer to Santa Clara County plus adjacent regions in southern San Mateo County and southern Alameda County
As more high-tech companies were established across San Jose and the Santa Clara Valley, and then north towards the Bay Area's two other major cities, San Francisco and Oakland, the term "Silicon Valley" came to have two definitions: a narrower geographic one, referring to Santa Clara County and southeastern San Mateo County, and a metonymical definition referring to high-tech businesses in the entire Bay Area

