against the Greeks because he was the king of Persia
when he defeat the king darius 3
Darius was a Persian.
King Darius led the Persians threw battle.
In 490 BC Greeks victoriously fought Persians in the Battle of Marathon in an attempt from King Darius I to subjugate Greece.
King Darius I.
In 499 BC several Greek cities in Asia Minor rebelled against Persian rule. To help their fellow Greeks, a few city-states in mainland Greece sent soldiers to join the fight against the Persians. The Persians put down the revolt, but Darius was still angry with the Greeks. Although the cities that had rebelled were in Asia, Darius was enraged that other Greeks had given them aid. He swore to get revenge on the Greeks.
He would have difficulty in doing that. He was King of Persia and leading them.
Darius the Great.
No - Darius I was not a Mede, he was Persian. And Persians and Medes were not black, they were Indo-European.
Notably , it was Alexander the great , the king of Macedon who defeated the Persian king Darius the 3rd .
The battle of Marathon was a result of the Persians under King Darius the First to punish the Greeks for supporting the Ionian Revolt where Sardis had been burned after capture . The battle was essentially where the Greeks defeated a Persian punitive expedition that failed .
The Persian king Xerxes, who led an invasion, with Athens one of the primary targets.