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.
Yunnan Province, or Yunnan for short, is one of the 23 provinces in China, located in the southwest and the capital of Kunming. Bounded by 21 °8 degrees north latitude, 29 °15 degrees north latitude, 97 °31 degrees east longitude, 106 °11 degrees east longitude, Guizhou and Guangxi in the east, Sichuan in the north, Tibet in the northwest, Myanmar in the west, Laos and Vietnam in the south, Yunnan Province has a total area of 394100 square kilometers. The topography of Yunnan Province is high in the northwest and low in the southeast, descending step by step from north to south, which belongs to the mountainous plateau topography, and the mountain area accounts for 88.64% of the total area of the province. The topography is bounded by the wide valleys of Yuanjiang Valley and the southern section of Yunling Mountains, and is divided into east and west topographic areas. The eastern part is the plateau of eastern and central Yunnan, which is part of the Yunnan-Guizhou Plateau, characterized by gently undulating low mountains and round hills.