Wallacea is home to languages of the Austronesian language family, and to languages from multiple Papuan, or non-Austronesian, language families. It has long been observed that the Austronesian languages of Wallacea display Papuan influences. Some linguists have attempted to define linguistic Wallacea (albeit under other names) in terms of this hybridity. The present article however shows that the zone of Papuan influence on Austronesian languages is much wider than Wallacea, encompassing areas east as well as west of New Guinea. Within this wider zone, called here Linguistic Melanesia, a more restricted Wallacean linguistic area can nevertheless be identified as a subcategory defined by a set of specific features not found elsewhere in Linguistic Melanesia. There is evidence that Linguistic Wallacea is the result of prehistoric interactions between Austronesian migrants and a pre-existing population of seafaring Papuan agriculturalists, who were already well established in Wallacea before the Austronesians arrived.