What is the historical background of Yan 'an?

Yan 'an is located in the north of Shaanxi Province, and the south bank of Yanhe River is the seat of Yan 'an Administrative Office. Listed as a famous historical and cultural city in China by the State Council, it occupies a special position in the modern history of China. 10, the 25,000-Li Li Long Long March of the Chinese Red Army of Workers and Peasants successfully arrived in northern Shaanxi. In June, 1935, the CPC Central Committee entered Yan 'an and became the capital of the Shaanxi-Gansu-Ningxia Border Region. From then on, Yan 'an became the world of China people.