The Spanish arrived in the area in the late 18th century, bringing missions, military outposts, and land grants. Much of what is now Newark was part of Rancho Arroyo de la Alameda, granted by the Spanish government to José de Jesús Vallejo, brother of the more well-known Mariano Vallejo, in 1842. This land grant changed hands over the years, eventually being subdivided as Americans and other settlers moved west during and after the Gold Rush era in 1848-1855.