Eras are the broadest historical unit of time, measuring hundreds of millions and even billions of years. Each Era may have multiple subunits known as Epochs. Historians divide Adnati’s history into three eras. The First Era covers the period of time when the earth was created. The Second Era covers the period of time when life on Adnati emerged, both plants and animals. The Third Era covers the emergence of intelligent hominid life, both on the surface and in the Underdark, including humans, elves, dwarves, orcs, goblins, and others.