I found this about The Dragons' Maw, maybe it'll help.
The Dragon's Maw
This tomb is only partially explorable without doing adventures. In order to explore it fully, you'll need the Keystone of the Dragon, which is acquired through a rather long quest chain that inolves a trip to France. See the Notable China Adventures section for 'Knowledge of the Past' to learn more. This place is the tomb of Dong Huo and his mummy resides at its lowest level. There are many hidden doors in this place concealing multiple nice treasures. Stumbling across the Symbol of the Temple of the Dragon should be no trouble at all.