The Bahrain burial mounds, or tumuli, take up a large land part of Bahrain Island: the mounds, ranging in size from almost invisible to 24 meters high have been variously estimated to number between 50,000 and 175,000. The large number of burial mounds situated on a relatively small island has resulted in several assertions as to their origin. A chart is provided which shows the average population size required to produce 150,000 dead persons in a given time period and with given life expectancy.