San Diego (/ˌsæn diˈeɪɡoʊ/ SAN dee-AY-goh, Spanish: [san ˈdjeɣo]; Spanish for 'Saint Didacus') is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States and the seat of San Diego County, the fifth most populous county in the United States, with 3,338,330 estimated residents as of 2019. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches and parks, long association with the United States Navy, and recent emergence as a healthcare and biotechnology development center. San Diego is the second largest city in the state of California, after Los Angeles.
Zhangxian, which belongs to Dingxi City, Gansu Province, has a poor name because of its important strategic position and is regarded as the "western barrier" of the Han Dynasty. Tianshi changed its name to Wuyang County in the second year of the Tang Dynasty, and changed its name to Zhangxian County during the Hongwu period of the Ming Dynasty. Zhangxian County is located in the central and southern part of Gansu Province, located in the transitional zone between the West Qinling Mountains and the Loess Plateau, Wushan County in the east, Zhuoni County in the west, Minxian County in the south, Longxi County and Weiyuan County in the north, with a total area of 2164.4 square kilometers and a population of 205876. Among them, non-agricultural population 19056 (2010), is a national poverty alleviation and development work key county. Zhangxian is "the hometown of broad beans in China" and "the hometown of Hippophae rhamnoides in China". It was named "Green County in China" by the China Environmental Protection Federation in August 2008 and was named by China in 2005.