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.
Mianning County, which belongs to Liangshan Yi Autonomous Prefecture of Sichuan Province, is located in the southwest of Sichuan Province, in the north of Liangshan Yi Autonomous Prefecture, adjacent to Xiaoxiangling in the east, Xichang and Yanyuan in the south, Muli and Jiulong in the west, and Bodhisattva Gang and Shimian County in the north. The total area is 4420 square kilometers. Mianning is located in the Panxi Rift Valley, and the Anning River and Nanya River originate in the territory. The Yalong River winds through the southwest and is known as the rice granary on the banks of the Anning River. It is a "major county of national grain production" and "a big county for pig transfer". More than 30 kinds of minerals have been proved to be of mining value, among which the reserves of rare earths rank second in the country. Mianning is an old revolutionary base. In 24 (1935), after the long March of the Red Army passed through Mianning, the Red Army was established to enter Sichuan.