 The Valley of Tijuana was explored the same year by Juan Crespí.In 1829 Santiago Argüello, a Californio and a major Mexican land grant ranchos owner, obtained ownership of a parcel of land known as Rancho Tía Juana and in 1889 was Tijuana officially founded on this parcel when descendants of Argüello and Agustin Olvera, an early Los Angeles pioneer, agreed to develop the city.The metropolitan region was historically united as part of the province of Alta California under the Viceroyalty of New Spain.