Imperial Aramaic was highly standardised; its orthography was based more on historical roots than any spoken dialect, and the inevitable influence of Persian gave the language a new clarity and robust flexibility. For centuries after the fall of the Achaemenid Empire (in 330 BC), Imperial Aramaic – or a version thereof near enough for it to be recognisable – would remain an influence on the various native Iranian languages. Aramaic script and – as ideograms – Aramaic vocabulary would survive as the essential characteristics of the Pahlavi scripts.