The Dothraki language was created by David J. Peterson for HBO‘s Game of Thrones (an adaptation of George R. R. Martin‘s A Song of Ice and Fire), and is spoken by the Dothraki people. In Martin’s universe, the Dothraki are a race of nomadic horse warriors that live across the Narrow Sea on a large steppe-like grass plain known as the Dothraki Sea. Though they have a city (Vaes Dothrak), they go there only to trade, and never stay for long, ranging wide across the Dothraki Sea and stopping in at the cities that dot the coasts (the Free Cities, Slaver’s Bay, etc.).
The language (as it is today) is an expansion of the small bits of Dothraki found in the first three books of A Song of Ice and Fire. It’s now a fully-functional, human-usable language with a vocabulary of over 3,000 words (and growing).
For introductory information about the language, check out the following resources: