Daniel 6:28 (ESV)

28 So this Daniel prospered during the reign of Darius and the reign of Cyrus the Persian.

It is God’s work that Daniel’s life was prosperous during the reign of Darius and Cyrus. At the royal court he served as God’s instrument to protect God’s people; to give them the opportunity to be allowed to return to their own country; and to also be protected in those early years of return. Prosperity for Daniel also implied prosperity for God’s people—for those who remained faithful to the Lord even in exile. Those faithful to the Lord in fact returned to the Promised Land during the reign of Cyrus. That was the time when Cyrus the Persian and Darius the Mede ruled together over the great empire of the Medes and Persians.