The city, owing to its prestigious and ancient history, continued to be an important site, however, with a large population, defensible walls and a functioning local cult for centuries.[5] Though the city did become one of the Achaemenid Empire's capitals (alongside Pasargadae, Ecbatana and Susa), retaining some importance through not being relegated to just a provincial city,[6] the Persian conquest introduced a ruling class which was not absorbed by the native Babylonian culture, instead maintaining their own additional political centers outside of Mesopotamia. Since the new rulers did not rely on Babylon's significance for their continued rule, the city's prestige had been irreversibly diminished.[6]