China had limited contact with the rest of the world during several periods in its history, particularly during the early centuries of its civilization. One notable period where China experienced isolation due to its geographical features—including mountain ranges and deserts—was during the early medieval period, particularly from the 3rd to the 7th centuries CE. During this time, the fragmentation of the Chinese empire and the general instability made long-distance trade and contact with foreign entities less frequent.
Additionally, during the Ming Dynasty (14th to 17th centuries), especially in the late 15th and 16th centuries after the voyages of Zheng He, China adopted a more isolationist policy, limiting international trade and contact with foreign nations.
However, the most significant periods of isolation were often influenced by internal dynamics, political stability, and external pressures rather than solely geographical location. The mountainous and desert regions did provide a natural barrier to contact, but the political context often played a more substantial role.