While the discovery of ossuaries in both Eastern and Western Iran dating to the 5th and 4th centuries BCE indicates that bones were isolated, that this separation occurred through ritual exposure cannot be assumed: burial mounds, where the bodies were wrapped in wax, have also been discovered. The tombs of the Achaemenid Emperors at Naqsh-e Rustam and Pasargadae likewise suggest non-exposure, at least until the bones could be collected. According to legend (incorporated by Ferdowsi into his "Shahnameh"), Zoroaster himself is interred in a tomb at Balkh (present-day Afghanistan).