I think not. Darius Mede may not be in the line of Darius I, II,
III. it's just a 'Darius" in Daniel who ordered Daniel to be put in
the lion's den. He could be coexisting with Cyrus II to oversee
Babylon while Cyrus II is King of Persia.
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Xerxes mother was Atossa, Darius I of Persia wife and Cyrus the
Greats' daughter.