Abstract The “Silk Road” has referred to the roads or the road networks that facilitated East–West communication, with ancient China as the starting point in the East. For a long time, the Qinghai-Tibet Plateau, known as the “roof of the world,” has not been included in discussions of the Silk Road, as it has been generally understood as dangerous for overland passage due to its location in the alpine snow region, challenging natural environment, and sparse population. As a result, few references on East–West passage through the plateau have been found in the historical records, in both the Chinese and Tibetan languages. However, archaeological discoveries in recent years have shown that from prehistoric times the early people on the Qinghai-Tibet Plateau began their communication and exchanges with the outside world in various ways. No later than the Han and the Jin dynasties, the traditional “Land Silk Road” had extended its trunk routes into the plateau. During the Tang dynasty, as the Tubo kingdom expanded continuously, it built a relatively stable transportation and road network that connected it with South, Central, and East Asia, which this article terms the “Plateau Silk Road.” The formation of the Plateau Silk Road was of great significance, as it not only connected the “Land Silk Road” and the “Steppe Silk Road” in North China as well as the “Maritime Silk Road” and the “Southwest Silk Road” in South China as a whole, but also played an irreplaceable role in integrating the western territories of China and the ethnic groups inhabiting these territories into the Chinese national community. In this process, the ancient people of all ethnic groups on the Qinghai-Tibet Plateau made important historical contributions.