Euripides (c. 480-406 BCE) was an extremely popular tragic poet who lived in Athens at the height of its radical democracy. This play was part of his last set of competitive tragedies. The group won first prize in the Greater Dionysia contest of 405, but Euripides died in 406, too early to see the victory.
The god of wine, theater, and madness, Dionysos (also called "Bacchus," hence his female worshippers are "Bacchae"), son of Zeus and Semele, returns to his native town of Thebes to take savage revenge on those who refuse to worship him -- driving all the women of the city mad, and sending the young king of Thebes, Pentheus, Dionysos' cousin, to a gruesome death.
As are the gods in many of Euripides' other plays, the god Dionysos here is portrayed as capricious, vengeful, and treacherous to humans. Yet the play also contains some of the most beautiful poetry ever written, describing the wild beauty of the countryside and its rivers and mountains, and urging mortals to submit to the ways of the gods and not to fight against them, and to live peacefully despite the terrible uncertainty of human life.