Stupa architecture was adopted in Southeast and East Asia, where it became prominent as a Buddhist monument used for enshrining sacred relics. The Indian gateway arches, the "torana", reached East Asia with the spread of Buddhism. Some scholars hold that "torii" derives from the torana gates at the Buddhist historic site of Sanchi (3rd century BCE – 11th century CE). In Tibet, the stupa became the chörten, and the pagoda in East Asia. The pagoda has varied forms that also include bell-shaped and pyramidal styles. In the Western context, there is no clear distinction between a stupa and a pagoda. In general, however, "stupa" is the term used for a Buddhist structure in India or Southeast Asia while "pagoda" refers to a building in East Asia which can be entered and which may be used for secular purposes. However, use of the term varies by region. For example, stupas in Burma tend to be referred to as "pagodas."