According to written histories, trepang fishers from Island Southeast Asia (“Makassans”) frequented coastal northern Australia from c.1750 to 1907 CE. Yolŋu oral traditions and old Austronesian borrow words in coastal Aboriginal languages suggest a long and complex history of foreign voyaging to northern Australia. Yet archaeological radiocarbon chronologies for the Southeast Asian trepang industry and earlier voyaging encounters are few and the dates have never been comprehensively reviewed. Only one Arnhem Land trepang fishery site has been dated extensively, and others have produced unusually old dates of c.1200–1500 CE. The Groote Eylandt rockshelter of Dadirrigka yielded an enigmatic sherd of friable earthenware above a radiocarbon date of c.1100 CE. Here we have compiled, reviewed and recalibrated all 49 radiocarbon dates directly associated with Southeast Asian contact sites, stratigraphy and rock art in northern Australia. We discuss the dates and their archaeological contexts region by region to assess their reliability. We also report for the first time Yanyuwa (southwest Gulf of Carpentaria) oral traditions which shed light on their past kinship and exchange relationships with Makassan visitors. The radiocarbon dates provide tentative support for four phases of interaction in northwest Arnhem Land and Groote Eylandt, including pre‐Makassan encounters and the organised trepang industry of the eighteenth and nineteenth centuries. There is a paucity of archaeological excavations and radiocarbon data from northeast Arnhem Land, the Kimberley and the southwest Gulf of Carpentaria, where historical writings, linguistics and oral traditions are still the most reliable indicators of the timing and nature of cross‐cultural interaction.