Kathmandu – Yatkha Bahal stupa and courtyard
Bahals are courtyards that originated as Buddhist monasteries. Most of the buildings that exist today in bahal courtyards date from the 14th to the present century, but the monasteries themselves are much older than even the oldest buildings. Records and stone monuments and sculptures in the courtyards show that Kathmandu was home to many bahals in the 5th century CE, and the oldest may date to as early as the 3rd century BCE.
John Child, Streets of Silver, Streets of Gold, p. 27