Belshazzar was before Darius.
Darius the Mede is known in The Bible record in connection to two famous incidents involving the prophet Daniel. Darius came to power when Belshazzar was deposed after the famous Writing On The Wall incident, and Daniel In The Lion's Den occurred during Darius's reign.
Daniel in the Bible if that is who you are talking about, served God.
Belshazzar was a 6th-century BC prince of Babylon, the son of Nabonidus and the last king of Babylon according to the Book of Daniel in the Hebrew Bible. In Daniel 5 and 8, Belshazzar is the King of Babylon before the advent of the Medes and Persians.
There is a Biblical Darius, "Darius the Mede", who assumes the throne of Belshazzar after Daniel deciphers the predictions of Belshazzar's demise. (Book of Daniel) * This is one source for the English idiom "reading the handwriting on the wall", which means seeing a future consequence. Three kings of Persia were named Darius, the first being "Darius the Great" (549-486 BC) and the other two later successors, Darius II (aka Ochus, king 423-404 BC) and Darius III (aka Artashata 380-330 BC).
Belshazzar was a king from the Old Testament.
Belshazzar is the Hebrew form of the Akkadian name Bel-sarra-usur; known to mean "Ba'al Protect the King," or "God/Lord Protect the King."
Some translations have "Queen Mother", which indicates she is Belshazzar's mother.
The mother to King Darius one was called Rhodugune.
King Darius led the Persians threw battle.
Rhodogune was the mother of Kind Darius of Achaemenid Empire.
Darius was a Persian.
king Cyrus and king darius