The Spartans were the 300 Greeks who stood off a whole lot of Persians. Sparta was one of many Greek city states of the time. Their sacrifice encouraged the other Greek city states to unite in the war against the Persians to prevent them from taking Greece.
Just a little nitpick friend
The Spartans were the 300 Greeks vs the "evil" Persian.
The way you worded that makes it seem like 300 Greeks vs Persian/Spartan enemies.
The Spartans were the 300 Greeks who stood off a whole lot of Persians. Sparta was one of many Greek city states of the time. Their sacrifice encouraged the other Greek city states to unite in the war against the Persians to prevent them from taking Greece.