Maenads were the followers of Dionysus, the Greek god of wine, grape harvesting, and ecstasy. They were real people and not mythical creatures. Maenads translates from Greek to 'madness' or 'raving ones', which described the frenzies that they would work themselves up in when participating in rituals for Dionysus.
I'm not too familiar with the intricacies of the Hellenic Pantheon, so I'll leave any further explain to people who actually know about this stuff.
But it's interesting, out of all the exotic and mythical creatures out there, you picked the ones that were actually human!