A dragons breath in the Mists
The five eras of Changeling history can be divided into the Mythic Age, the Sundering, the Shattering, the Interregnum, and the Resurgence.
The Sundering lasted from circa 1000 BC to 1200-1400 AD, when folks started to stop believing in the Fae, and the pressure of Banality began to build. Early on in the Sundering, the Dreaming came into existence as separate areas from the Mundane World possibly as a buffer zone to keep the dreams of Mankind from changing Arcadia itself. Mid-way along in the Sundering, the Mists were established as the split grew between the mundane and the mythic, causing the records and evidence of dragons and unicorns and suchlike bygone beasts to be dismissed by the mortal mind