LEONIN (1183-1238?) - A member of the "School of Notre Dame" Perotin and Leonin were choirmasters at the Church of Notre Dame (predecessor to the cathedral now known by that name). They were thought to be the first composers of polyphonic music.'

A text summary of the clickable map above, meant for web-crawlers and other automatic tools:
Leonin was collegue of Perotin
Leonin has dates 1183-1238?
Leonin composer during Middle Ages
Leonin is member of School of Notre Dame
Leonin thought to be first to compose polyphonic music
Leonin had position choirmaster