Radiocarbon determinations suggest that the earliest pottery thus far identified on the Sepik coast, which we have called Nyapin Ware after a locality on Tumleo Island, dates back to the interval 2,000–1,500 BP (95% highest posterior density [HPD]). A more precise estimate can be made for the Sumalo Ware as currently known in the Aitape area. Analysis suggests that Sumalo Ware was locally in use over a period of between 5 and 270 years (95% HPD) beginning some time in the interval 1,400–1,200 BP (95% HPD). Additionally, a local marine ΔR of 1,005 ± 80 can be estimated for this location.