Made in both ceramic and bronze, censers in this shape are now commonly known as Mount Bo or boshan incense burners. The use of these censers can be traced to the prevailing interest in magical paradises and immortality. Mountainscapes are often interpreted as images of the mythical land of Penglai, an imaginary mountain paradise inhabited by immortals and other semidivine creatures, said to be located in either the western mountains or the eastern seas. Belief in magical worlds such as Penglai had begun as early as the 4th century BCE. By the Western Han period (206 BCE-CE 9), interest in the land of the immortals had become more widespread and more concrete. It was believed that such a paradise could be found and that an elixir of immortality could be obtained there.
The mountaintops of this type of censer were made in two parts and open in the center to allow for the placement and lighting of incense. The smoke from the incense escapes through small holes cleverly hidden in the top part of the mountains. The smoke was believed to represent cloud-breath, or yunqi, an auspicious omen that was generally depicted in the visual arts as trailing wisps of smoky clouds. The sight of the smoke rising from a censer such as this one would have been interpreted as a tangible manifestation of cloud-breath, making such censers invaluable tools for adepts in the various cults of immortality. Such censers were also used, however, to mask odors in bathrooms and to perfume the air at banquets.