The Dark Gate was a portal that the Black Moon Clan tried to create in order to allow the power of the Evil Black Crystal to be poured out upon Earth in the present day. Esmeraude first tried to open the Dark Gate by planting specially created Dark Henge, which would grow until they were large enough for the Gate to open. The plan eventually failed and was abandoned.
Later, Wiseman attempted to open the Dark Gate once more, with the assistance of Black Lady and Prince Demande. After Wiseman was destroyed with the power of the two Silver Crystals, his Gate also disappeared.