I'd suggest some Indigenous Western Hemisphere civilizations, myself. Even by the 18th Century, they hadn't all been wiped out (in the terms of CivII civilizations being wiped out, at least). A fair number of them still held their ancestral homelands, like the Inuit, Aleuts, and Northern Tribes, Northwest Pacific Tribes, Navajo, Apache, Commanche, etc., Cherokee, Creek, Iroquois, and Objibawa in some areas, Amazonian Tribes, Miskito, and far south tribes like Mapuche, Guarani, Yamana, etc., or, like the Council of Seven Fires or Iron Confederacy, for examples, moved away from initial European settled lands to what were then sparsely inhabited areas. A few Maya Kingdoms remained unconquered in that Century, and the Seminole Nation has just having it's ethnogenesis from fractured tribes in what is now the Southeast US and apparently a fair number of escaped Black Slaves, formed in what is now Florida. They held and governed these lands at this time as effectively sovereign nations, despite the claimed borders and claims on European maps at that time.
