From Babylon, Alexander went to Susa, one of the Achaemenid capitals, and captured its treasury. He sent the bulk of his army to the Persian ceremonial capital of Persepolis via the Persian Royal Road. Alexander himself took selected troops on the direct route to the city. He then stormed the pass of the Persian Gates (in the modern Zagros Mountains) which had been blocked by a Persian army under Ariobarzanes and then hurried to Persepolis before its garrison could loot the treasury.