San Diego is the second largest city in California and the seventh largest city in the United States. It is located at the southern end of the state on the Bay of San Diego, 20 kilometers south of the Mexican border, with an urban area of 829 square kilometers and a population of 1.3 million. It is of Mexican and Spanish descent; The metropolitan area includes nearby beaches and highlands, with an area of 11020 square kilometers; The metropolitan area includes 18 small cities with a total population of over 2.8 million people. Some call it the 'City of Mixed Blood'

San Diego was originally the hometown of American Native Americans on the southern California coast. The land here is fertile, the climate is warm, and the ocean resources are abundant. Native Americans make a living here by farming, fishing, and hunting. 16、 In the 17th century, European explorers came here and disrupted the lives of Native Americans, beginning the period of European colonial rule. In 1542, Portuguese explorers first arrived at the port of Santiago, and during the "Age of Navigation" that followed, European and Atlantic countries also came to this very remote place at that time.