On the other side is the first treasure and when you follow the corridor, you get into a room with a big hole in the floor and with the Stele.
To get out, you can move the 2 bookshelves close to the Stele, or you can go down the hole. - Careful! The ground is full of snakes.
After killing the snakes, follow the path out, until you get to another 2 shelves to move. Do so, go through, smash the wall and you're out.