The last major tsunami in the Indian Ocean was about A.D. 1400. In 2008, a team of scientists working on Phra Thong, a barrier island along the hard-hit west coast of Thailand, reported evidence of at least three previous major tsunamis in the preceding 2,800 years, the most recent from about 700 years ago. A second team found similar evidence of previous tsunamis in Aceh, a province at the northern tip of Sumatra; radiocarbon dating of bark fragments in the soil below the second sand layer led the scientists to estimate that the most recent predecessor to the 2004 tsunami probably occurred between A.D. 1300 and 1450.