Is anyone out there? For today’s #30DayMapChallenge, “NULL,” we want to consider the troubled history of showing nothing on a map. Null space on a map can represent the absence of information—and it can also represent the deliberate omission of people who the mapmaker would prefer to leave off. Sometimes these two conditions weave confusingly together, with ignorance propping up a convenient fiction of emptiness.

This map, based on the Verrazano voyages of 1524, is one of the earliest depictions of the coast of northeastern North America. Europeans had only surveyed the coast, so the mapmaker, Giovanni Battista Ramusio, left a giant section of the map blank, labeling it “Parte Incognita,” or “unknown part.”

Ramusio knew that North America was already inhabited; this woodcut shows illustrations of Indigenous people hunting and dancing. But the legal principle of “terra nullius”—or “empty land”—provided the basis for many European claims to new territory in the Western Hemisphere. Ignorance and motivated reasoning blended together, as Europeans chose to pretend that Indigenous people were not permanently settled on the land and thus had no title to it. This opened the way for royal authorities to bring land under their own legal sovereignty.

The terra nullius doctrine has been challenged by anti-colonial movements. Indigenous rights activists won a victory in Australia’s 1992 Mabo case, in which the High Court of Australia specifically rejected the legal assumption that Indigenous Australians had no title to land prior to British occupation.

Beyond the narrow legal definition, the “terra nullius” principle lurks through the historical geography of the United States, whenever we set “the beginning” at the moment that Europeans arrive. That which is unmapped is not necessarily empty—and we should always keep in mind whose convenient fictions are propped up by a map’s “null” areas.