According to later Zoroastrian legend ("Denkard" and the "Book of Arda Viraf"), many sacred texts were lost when Alexander the Great's troops invaded Persepolis and subsequently destroyed the royal library there. Diodorus Siculus's "Bibliotheca historica", which was completed circa 60 BCE, appears to substantiate this Zoroastrian legend. According to one archaeological examination, the ruins of the palace of Xerxes bear traces of having been burned. Whether a vast collection of (semi-)religious texts "written on parchment in gold ink", as suggested by the "Denkard", actually existed remains a matter of speculation, but it is unlikely.