Why Did The Persians Conquer Greek

During the 5th century BC, Persian King Darius I led his people in many attempts to conquer Greece. The Persians invaded Greece due to the support the Athenians provided the Ionians when they were trying to overthrow the Persians. During the Ionian revolt, the Persians were defeated in Sardis with the help of Athens, consequently King Darius, for obvious reasons, held a grudge against Greece and was determined to destroy Athens. These events led to the Battle of Marathon, one of the earliest battles to be recorded in history and considerably the most defining event in Greek culture. (A History of Greece)
In the year 490 BC, King Darius sent his navy, consisting of 600 ships, to Greece, they arrived just north of Athens, at the coast of Marathon.