The formation of Wutai Shan beliefs in medieval China is significant in several ways, among which the most conspicuous is the opening of a new dimension for the spread of Buddhism in China. A sacred mountain is different from a simply famous or faction-based mountain; it controls all of the surrounding areas and constitutes the nexus of religious activities. Manjusri worship is central to Wutai Shan beliefs. A number of traces and relics of ostensible Manjusri appearances are physical attractions of the belief system. Temples in Wutai Shan and their monks form the basis of the sacred mountain culture, while pilgrims complement the ceremonies. The "Map of Wutai Shan" and Qingliang Zhuan are two masterpieces that promulgate the beliefs. Wutai Shan became a destination of pilgrimage after being recognized as a Buddhist sacred mountain. From the Tang dynasty, apart from the genuine Wutai Shan in Shanxi province, there appeared elsewhere in China such places as Little Wutai and South Wutai. Furthermore, monks from Korea and Japan brought the beliefs back home and created their own sacred mountains in the image of Wutai Shan, which became a common phenomenon in the Buddhist cultural sphere. This article focuses on the process of Wutai Shan beliefs spreading from China to neighboring countries as an example of the development and variations of East Asian Buddhism.