For ten points, identify this horse breeding people subjugated by Cyrus the Great, who had their capital at Ekbatana.
They were divided into six tribes, including one called the Magi, and, according to Herotudus, Deioces united them in the 8th century BC.  A total solar eclipse on May 28, 585 BC, caused an army from this country led by Cyaxares to abort a battle with the Lydians and negotiate a peace treaty.  An alliance with the Babylonian ruler Nabopolassar culminated in the conquest of the Assyrian capital of Nineveh in 612 BC.  For ten points, identify this horse breeding people subjugated by Cyrus the Great, who had their capital at Ekbatana.
They were divided into six tribes, including one called the Magi, and, according to Herotudus, Deioces united them in the 8th century BC.  
Medes or Media