I thought it might be a good idea to compile some of the fluff out there regarding E'n myths -- thing that don't necessarily deserve a full write-up, but maybe should have a footnote somewhere.

Ys: A mythical island kingdom that the gods sunk into the sea as punishment for their use of dark magics. The legend is widespread, but generally considered apocryphal.

Thet: One of a number of dwarven city-states that existed before the Time of Darkness. Thet and the other cities are fairly obscure, but they existed and made extensive use of the waygate system.