Tibetan art can be viewed and remembered in many different ways. For the traveller who has visited one of the regions of Tibetan culture, Tibetan art may signify the colourful interiors of the monasteries he or she has visited with sculptures of different sizes, walls covered with murals and practically every corner of the structure decorated in some form, an interior that contrasts markedly with the soft tones of the high altitude desert landscape outside. The collector will tend to think of the colourful scroll paintings or thangkas, and dazzling bronze sculptures of different ages and quality offered by auction houses and art dealers all over the world. The visitor to a museum may also think of everyday products of skilled craftsmanship and often somewhat crude appearance found in many museum collections in addition to thangkas and bronzes. All of them will certainly also have some of the aspects in mind that are so strange to a western beholder with a Christian background, in particular the fierce deities, often with multiple heads-some of them animal heads-arms and legs, or those in sexual embrace, the so-called father-mother (Tib. yab-yum) images. Few people, however, will consider clay as an important artistic medium in Tibetan art. Nevertheless, in Tibet clay has always been the sculptural material par excellence.2 That said, some may now remember the small relief sculptures of this material which are found all over Tibet and occasionally seen in museums. These are mass-produced with the help of moulds, contain a relic, and are often deposited in the so-called chörten (Tib. mchod-rten, Skt. stapa), those votive structures of different sizes deriving from a funerary monument that are found all over the Tibetan landscape and are particularly abundant in the Western Himalayas. The practice of making and depositing these relief sculptures, called tsha-tsha in Tibetan, has its roots in Indian Buddhist practice as is proven by the baked clay tablets of Burma and the moulded clay tablets found at Nalanda (a Buddhist University excavated in present-day Bihar), together with the so-called Gilgit stapa (Northern Pakistan) and Afghanistan.3 Although mass-produced, some of these tsha-tsha are very sophisticated and a number of them are even painted, such as the one shown in Figure 1. This c. 13th-century tsha-tsha from Shalu monastery in Central Tibet shows a four-armed form of the Bodhisattva Avalokiteshvara, the 'Lord of the six syllables' (Skt. Sadaksaralokeshvara; Tib: sPyan-ras-gzigs yi-ge-drug-pa), the name referring to the mantra Om mani padme ham that is engraved on almost any flat stone in the region. Indeed, Tibet is considered the special field of activity of this deity.4 These Bodhisattvas are beings that have taken a vow to become a Buddha, postponing their own enlightenment for the benefit of all other beings. Like the practice of making and depositing tsha-tsha, much of Tibetan art derives from India, either directly or via mediators such as Nepal. However,