Before it meant anything on the internet, Tartary (Latin: Tartaria) was a real, working term in European geography, cartography and diplomacy β in continuous use from roughly the 13th century through the late 19th century. It referred, loosely and inconsistently, to the vast stretch of Central Asia and Siberia: from the Caspian Sea and the Volga in the west to the Pacific coast in the east, and from Persia and India in the south up to the Arctic Ocean.
The word derives from "Tartar" (also "Tatar") β the name Europeans applied broadly to Turkic and Mongolic peoples of the steppe, a group that was never ethnically or politically unified. The Library of Congress's own map division states it plainly: the region labelled "Tartary" never seems to be in quite the same place on two different maps.