And Daniel was [there] until the first year of Cyrus the king.

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

In the third year of Cyrus [the] king of [the] Persians, a word was revealed to Daniel, who was called [by] his name Belteshazzar, and the word [was] reliable and [it concerned] a great tribulation, and he understood the word and {he received understanding}.