The stupa was enlarged on five occasions during the following centuries, every time by building over, and encapsulating, the previous structure.
The stupa was excavated by an Italian mission (IsIOAO: Istuto Italiano per l'Africa e l'Oriente), led by archaeologist Domenico Faccenna from 1956, to clarify the various steps of the construction and enlargements. The mission established that the stupa was "monumentalized" by the addition of Hellenistic architectural decorations during the 2nd century BCE, suggesting a direct involvement of the Indo-Greeks, rulers of northwestern India during that period, in the development of Greco-Buddhist architecture.
An Indo-Corinthian capital representing a Buddhist devotee within foliage has been found which had a reliquary and a coins of Azes II buried at its base, securely dating the sculpture to earlier than 20 BCE.
The nearby Hellenistic fortifications of Barikot are also thought to be contemporary.
- "De l'Indus a l'Oxus: archaeologie de l'Asie Centrale", Pierfrancesco Callieri, p212: "The diffusion, from the second century BCE, of Hellenistic influences in the architecture of Swat is also attested by the archaeological searches at the sanctuary of Butkara I, which saw its stupa "monumentalized" at that exact time by basal elements and decorative alcoves derived from Hellenistic architecture".
- The Turin City Museum of Ancient Art Text and photographic reference: Terre Lontane > O2
- Report of the Italian Archaeological Mission (Pdf, Italian)
- Domenico Faccenna, Butkara I (Swat, Pakistan), 1956–1962, Roma, 1962-1981.