The Frisii were an ancient tribe, who were neighbours of the Roman Empire in the low-lying coastal region between the Rhine and the Ems rivers, in what what is now the northern Netherlands. They are not mentioned in Roman records after the third century, and archaeological records show that there was population decline, and frequent flooding caused by sea level rise. It is probable that many Frisii were among the early "Saxons" who settled in Britain. They are nevertheless also likely to be ancestors of the Frisians of today, whose material culture can be traced back to new settlements in the early Middle Ages.