Womb of the World
The Womb of the World is a large lake that lies just west of Vaes Dothrak and the Mother of Mountains. It is a holy place to the Dothraki people. The lake is surrounded by reed, and is reported to have no bottom. A river runs from the lake north through the Kingdom of the Ifequevron to the Shivering Sea.
A Game of Thrones
After eating the heart of a stallion as part of a ceremony for her child, Daenerys Targaryen rides to the lake and bathes naked to remove the blood. Afterwards she has sex with Khal Drogo on the shore.