The Achaemenid and Seleucid dynasties of ancient Persia conquered and ruled multinational and multicultural empires based on what is today Iran. Although created by force of arms, the kings of these dynasties ruled with respect for the customs, cultures, and religions of their subject peoples. Their dynasties flourished when these rulers and the peoples they ruled reached accommodation with one another. Unfortunately for both dynasties, their empires were often fragile and always beset with hostile rivals.