The Wallacean archipelago is a renowned hotspot for human linguistic and genetic diversity, testimony to a deep history that spans more than 50,000 years. Like their neighbours in Australia and New Guinea, the Indigenous peoples of Wallacea are thought to have remained isolated from outside groups, and each other, for more than 45,000 years until the introduction of new genes and languages by Austronesian seafarers some 3.5 thousand years ago (kya). This static view of Wallacean history has been challenged by converging interdisciplinary evidence, however, which documents the transformation of Wallacean societies by the back-migration of Papuan peoples from neighbouring New Guinea from the as early as the Last Glacial Maximium ~15 kya. In this talk, I discuss results from a genomic study of >250 genomes from Wallacea and West Papua that explores the origins, timings, and impacts of historical Papuan back-migrations across Wallacea, summarising key findings and their implications for our understanding of the peopling of Sahul.