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.
Helan County (Pinyin: Helan Xian), under the jurisdiction of Yinchuan City, Ningxia Hui Autonomous region, is located in the northern part of Ningxia Hui Autonomous region, bought Lian County in the Western Han Dynasty, and changed its name to Helan County in 1941. As of 2013, Helan County covers an area of 1599 square kilometers. As of 2018, it has jurisdiction over 4 towns, 1 township, 3 fields and 1 management committee. In 2016, the total population of Helan County (resident population) was 255995. Helan County is located in the northwest inland of China's Loess Plateau, in the middle of the Qingtong Gorge irrigation area in Yinchuan Plain, mountainous area in the west and plain in the east. The basic characteristics of the topography trend are high in the southwest and low in the northeast, with a distorted surface tilting from southwest to northeast. The whole area is mainly composed of western mountain and eastern plain.