Where did the theory of Atalntis start?

The story of Atlantis as far as the Greeks are concerned had it's origins in Egypt. Plato's
great- grandfather Dropides copied it word for word from the Egyptian priest Solon, who had studied the tale himself from the temple archives. The tale was supposedly authored by the scribe of the gods and inventor of Egyptian writing Thoth(gr)or Djehuty()egyp). Who had survived the sinking of Atlantis and brought civilization and the first egyptians with him.