Stupas originated as pre-Buddhist earthen burial mounds, in which ascetics were buried in a seated position, called chaitya. After the parinirvana of the Buddha, his remains were cremated and the ashes divided and buried under eight mounds with two further mounds encasing the urn and the embers. Little is known about these early stupas, particularly since it has not been possible to identify the original ten monuments. However, some later stupas, such as at Sarnath and Sanchi, seem to be embellishments of earlier mounds.
The stupa was elaborated as Buddhism spread to other Asian countries becoming, for example, the chorten of Tibet 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 the stupa and the pagoda. In general, however, stupa is used for a Buddhist structure of India or south-east Asia, while pagoda refers to a building in East Asia which can be entered and which may be secular in purpose.
Stupas were built in Sri Lanka soon after King Devanampiyatissa converted to Buddhism, the first stupa to be built was the Thuparamaya. Later on Sri Lanka went on to build many stupas over the years, some like the Jetavanarama in Anuradhapura being one of the tallest ancient structures in the world.