The current ethnographic map of the northern Caucasus mountains shows scattered groups of Circassian people, now numbering roughly 750,000 in Russia. In 1850, however, the Circassians occupied the entire northwestern quadrant of the Greater Caucasus range. But as the Circassians refused to submit to imperial Russian rule, the Russian military engaged in a campaign of displacement and extermination. As reported by Wikipedia, “The Circassian genocide, or Tsitsekun, was the Russian Empire’s systematic mass murder, ethnic cleansing, and expulsion of 80–97% of the Circassian population.” Most of the few Circassians who managed to remain in their homeland were Kabardians, members of the easternmost of the twelve Circassian groups (or “tribes”). The western groups were essentially eliminated. As noted in a different Wikipedia article:
The Zhaney were a very powerful Circassian tribe in the past. They lived the north of the Natukhai tribe’s land on the coast of the Black Sea and Azov Sea in Eastern Europe. … As a result of the bloody Russian-Circassian War, Zhaney tribe was almost wholly destroyed, as only 3 families survived.
After their genocide and expulsion, the Circassian people largely vanished from the historical memory of the West, just as “Circassia” disappeared from its maps. In earlier times, Circassia had been well-know and well-represented, appearing prominently on many maps. On a 1744 map of Asia by George Willdey, for example, “Circassia” is depicted as one of the primary divisions of the Asian continent. As it is difficult to see this representation on the map as it can be reproduced here, I have re-outlined and re-labeled Willdey’s divisions on the second map posted below.
Willdey’s map seems to be an outlier, as no others that I have seen give Circassia such a prominent position. But Circassia was often mapped as covering a large area – much larger, in fact, than the area occupied by Circassian people circa 1850. In a Latin-labeled map of 1716 by Johann Baptist Homann, for example, Circassia is shown as extending along the eastern shore of the Sea of Azov, covering much of the steppe zone north of the Caucasus Mountains. Intriguingly, Homann labels the area as a kingdom: “Circassia, seu Regio Circassiorum.” Similar patterns are seen on French-language maps of the same period. An uncolored Nicholas Guedeville map of 1718, for example, shows “Circassie” as extending from the Sea of Azov to the Caspian Sea. It excludes, however, part of the Circassian homeland along the Black Sea coast, labeling it instead as belonging to Abkazia (“Abcassie”).
Nineteenth-century depictions of Circassia typically exclude some of the northern lowland areas included on Homann’s and Guedeville’s maps, but cover most of the northern Caucasus and its lowland fringe, often extending to the Caspian Sea (see Woodbridge map of 1828 posted below). In an unusual French map of 1863, the coloring scheme depicts “Circassie” as a two-part region, interrupted by the lands of the Ossetian (“Ossetes”) people of the central Caucasus Range. Maps published in the United States at the time often depicted an expanded Circassia, shown as extending from the Black Sea to the Caspian Sea (see the detail from a Jacob Monk map of the world, published in Baltimore in 1859, that is posted below). 
The geographical category of “Circassia” could even extend into the Black Sea itself. In a 1693 map by Vincenzo Coronelli, for example, the waters of the northwestern portion of the sea are labeled “Mare de Circassia Caucaseum”
By the late 1800s, however, the label “Circassia” had essentially disappears from maps made in Western Europe and the United States. Genocide, in other worlds, was followed by cartographic erasure, as will be explored in more detail in the next GeoCurrents post.