The five eras of Changeling history can be divided into the Mythic Age, the Sundering, the Shattering, the Interregnum, and the Resurgence.
The period of no sidhe nor True Fae on Earth, with the remaining 'watered down' changelings having to fend for themselves after the final death-throes of the Shattering around 1500-1600 AD is the Interregnum, as changelings had to try to work out how to survive on their own. A very rare few still had occasional access to the Dreaming, but Arcadia was either completely detached from the Mundane World or perhaps as some rumoured, had been destroyed. The sidhe and True Fae in Arcadia also didn't know if the Mundane World had survived the Shattering, some believing that its time had ground to a halt.