Daniel 9:1

In [the] first year [of] Darius, [the] son of Ahasuerus, from [the] offspring of [the] Medes, who became king over [the] kingdom of [the] Chaldeans--

Daniel 11:1

"And I, in the first year of Darius the Mede, {I stood} as a support and as a protection for him.

Daniel 1:21

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

Daniel 5:31-1

And Darius the Mede received the kingdom {when he was about sixty-two years old}.

Daniel 6:28

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

Treasury of Scripture Knowledge

Summary

In the first year of Darius the son of Ahasuerus, of the seed of the Medes, which was made king over the realm of the Chaldeans;

Bible References

Darius

Daniel 1:21
And Daniel was [there] until the first year of Cyrus the king.
Daniel 5:31
And Darius the Mede received the kingdom {when he was about sixty-two years old}.
Daniel 6:1
{It pleased Darius}, and he set up one hundred and twenty satraps over the kingdom, that they were {throughout the whole kingdom},
Daniel 11:1
"And I, in the first year of Darius the Mede, {I stood} as a support and as a protection for him.