Lythannya is located in the marshland of Mathonis on its eastern coast. There are a large number of small islands that stretch from the mainland of Mathonis to the elven empire of Rirollywyn. There is also a vast cave system that leads to the Underdark beneath Lythannya. It was by using these caves that the Drow were able to seize this land from the kingdom of Martoll.
Lythannya is a theocracy, ruled by the highest priestess of Lolth. It is a very feared place, and the only race known to have a large presence there are the Drow. Most other people are killed on sight.
Lythannya has been at war with Martoll for decades now, but it is believed that the true target is Rirollywyn, their elven cousins to the east.