Although vampiric entities have been recorded in many cultures and in spite of speculation by literary historian Brian Frost that the "belief in vampires and bloodsucking demons is as old as man himself", and may go back to "prehistoric times", the term vampire was not popularized until the early 18th century, after an influx of vampire superstition into Western Europe from areas where vampire legends were frequent, such as the Balkans and Eastern Europe, although local variants were also known by different names, such as vrykolakas in Greece and strigoi in Romania.