Daniel 1:21 New English Translation

²¹Now Daniel lived on until the first^[a] year of Cyrus the king.

Daniel 1:21 sn The Persian king Cyrus’ first year in control of Babylon was 539 b.c. Daniel actually lived beyond the first year of Cyrus, as is clear from 10:1. The purpose of the statement in 1:21 is merely to say that Daniel’s life spanned the entire period of the neo-Babylonian empire. His life span also included the early years of the Persian control of Babylon. However, by that time his age was quite advanced; he probably died sometime in the 530’s b.c.

New English Translation (NET)