Cyrus the Great is known for being the ‘great’ king of Persia. His empire was very big. The biggest in the world at that time. It reached from Asia Minor to India.
After the Medes, who Cyrus came from, won a war with the Assyrians, it was divided in half between the Medes and the Babylonians. The Medes got North and East. The Babylonians got South and West. When Cyrus came to power he united the Medes, Persians, and Lydians into a new empire. Cyrus claimed power over all the Medes and Persian kingdoms. Many of the kings were his relatives and so they submitted to him willingly. This established the official Persian empire. While Cyrus was king he actually conquered Babylon which was a big deal. His daughter married Darius the Great who would be another great king. While in reign he let the Hebrews go back and rebuild Jerusalem.
Cyrus the Great was succeeded by his son Cambyses the second who reigned for many years. According to some journal writings his reign was not a happy one.