I recently listened to the Dan Carlin podcast about it, and though it is interesting, you can never be sure on his accuracy.
Cyrus the Great was a Persian king and the founder of the Achaemenid dynasty (Darius, Xerxes, and even the Ptolemies and Seleucids traced back to this Royal line).
He was honestly just a really spectacular ruler and his empire stretched from Asia Minor to India. He had a profound impact on both Eastern and western culture, philosophy, religion and inspired leaders from Alexander the Great to Thomas Jefferson. Under him literature, religious freedom and general quality of life flourished and his legacy still influences the world today in many ways.