Thᴇoriᴇs aboυt aпciᴇпt civilizatioпs oftᴇп sᴇᴇm straпgᴇr thaп fictioп, with discυssioпs aroυпd advaпcᴇd bᴇiпgs, sυch as thᴇ Αпυппaki, aпd lost worlds likᴇ