Some time after the appearance of the Harbingers, a madness will effect all women in the capital, such that they attempt to eat their own infants. This may be ended by extraordinary supplications to the gods, such as the building of great temples filled with precious stones.
Then the rulers will go mad with cruelty, having the innocent torn apart by wild horses. They will believe passers-by to be trees or vines, and mutilate them with axes
Then the women of the capital again become mad and eat their own infants- or, if their infants are already eaten, themselves- but this time there will be no remedy.
Then the women will become birds, the land will become barren, and the empire will fall.
(thanks to noisms for his research on this topic)