The Achaemenid Dynasty is a dynasty in the ancient Persian Empire.
The founder of this dynasty was supposedly King Achaemenes of Anshan (Hakhamanish). He was succeeded by his son Teispes of Anshan. Inscriptions indicate that when the later died, two of his sons shared the throne as Cyrus I of Anshan and Ariaramnes of Persia. They were succeeded by their respective sons Cambyses I of Anshan and Arsames of Persia. In 559 BC, Cambyses the Elder was succeeded as King of Anshan by his son Cyrus II the Great. The later also succeeded the still living Arsames in the throne of Persia. Cyrus II is considered to be the first king of the Achaemenid dynasty to be properly called so, as his predecessors were subservient to Media. Cyrus II managed to conquer Media, Lydia and Babylon while his son Cambyses II added Egypt to the Empire.
The absolute zenith of its power was achieved during the reigns of Darius I (521 BC-485 BC) and his son Xerxes I (485 BC - 465 BC). These rulers built great, beautiful palaces in the ancient cities of Persepolis, Susa and Ecbatana. The Persian Empire too reached its greatest extension in this period.
After the death of Xerxes I (465 BC) the decline of the dynasty began. Persia saw a sequence of weak rulers ruling the empire. Decadence became rampant and army, finance and government administration were neglected.
At the height of their power, the Achaemenid rulers of Persia ruled over territories roughly emcompassing some parts of Iraq, Egypt, Syria, Pakistan, Jordan, Israel, Lebanon, Armenia, Central Asia, Caucasia and the Asian portion of Turkey. At different times, the Achaemenids also ruled Egypt, although the Egyptians twice regained their independence from Persia.