The Kabul valley was part of the Median Empire (c. 678–549 BC). In 549 BC, the Median Empire was annexed by Cyrus The Great and Kabul became part the Achaemenid Empire (c. 550–330 BC). During that period, Kabul became a center of learning for Zoroastrianism, followed by Buddhism and Hinduism. An inscription on Darius the Great's tombstone lists Kabul as one of the 29 countries of the Achaemenid Empire.