This video details the The Battle of Thermopylae in Greece in 480 BC, where only 7,000 Greek Spartan soldiers fought 300,000 soldiers from the invading Persian Empire, being outnumbered 50:1.  Along with explaining the circumstances of the conflict, the video also details the harsh practices of the Spartan warrior culture at the time, and it explains the advanced armor and weapons that the soldiers used.  The Spartans were not typical of all Greeks, and in fact they were often adversaries of the other Greek city-states such as Athens, who they frequently had conflicts with.