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.
Lankao, a county under the jurisdiction of Kaifeng City, Henan Province, and Zhiguan County, Henan Province, is located at the last bend of the Jiuqu Yellow River, with a total area of 1116 square kilometers and a total population of 859100. It is an important part of "half-hour traffic circle" in "one pole, two circles and three layers" in Henan Province. Lankao County was a household in the Spring and Autumn period, and Jiyang County was the beginning of Lankao County in the Qin Dynasty. In 5 BC, Emperor Liu Xiu, Emperor of the Han Dynasty, was born in the Jiyang Palace in the north of the county. In 9 years, it was changed from Dongfen County to Dongming County. In 1218, Dongming County was abandoned as Tongan Castle, and the new county seat was moved to the old land of Yuanggu County in the north of the Yellow River. In 1232, the south of the Yellow River was divided into two counties: Lanyang County and Yifeng County. In March 1783, the county seat of Kaocheng County moved to Lankao County for the first time. In 1825, Yifeng County was merged into Lanyang County, known as "Lanyi County".