The Thule Inuit migration eastward from Alaska is one of the great events in the Arctic past, yet many aspects of this process, including its timing, remain unclear. In this paper, we present new dates for the earliest known Thule sites in the Amundsen Gulf / Beaufort Sea region: Nelson River and Washout. This region acted as a "bottleneck" through which Thule migrants would have to pass, and therefore accurate dates for these two early sites have important implications for our understanding of the timing, rate, and nature of the Inuit peopling of the Eastern Arctic.