The Mother of Mountains is a mountain in Essos, located within sight of Vaes Dothrak, a lone mountain in the middle of the plains of the Dothraki Sea. It is considered sacred in the Dothraki religion.
In the books
In A Song of Ice and Fire, the Mother of Mountains is a mountain sacred to the Dohtraki people, located within sight of Vaes Dothrak and a lake known as the Womb of the World, from which, according to myth, the first man emerged riding on the first horse. Only men are allowed to set foot on the Mother of Mountains.