scholars believe that two severe droughts, one from 1587 to 1589 and another from 1607 to 1612, drove the bearer of the Monongahela culture from the region in search of a more habitable area. Because of trade with other groups, the Monongahela could have contracted infectious diseases from coastal peoples, who were directly exposed by their contact with Europeans. As the Native Americans did not have immunity, the new diseases resulted in high fatalities in widespread areas. The Monongahela culture was progressively disappearing before the time the Iroquois League invaded the Allegheny Plateau through to the Lake Erie region in an effort to control new hunting grounds for the lucrative fur trade. The powerful Iroquois likely conquered or drove out the Monongahela. About the year of 1635, it appears that a group of refugees from the Monongahela culture resettled in south-central Virginia at Halifax County. They were likely absorbed by a Siouan-speaking tribe of the area, but historians do not know for sure. There were also Algonquian and Iroquoian-speaking tribes nearby. See also Prehistory of West Virginia Protohistory of West Virginia References External links Monongahela Culture, Virtual First Ohioans "Ghosts of the Mountains", a video of Somerset County Archaeology, Pennsylvania, the working of sites of Monongahela people Late Woodland period Archaeological cultures of North America Native American history of Maryland Native American history of Pennsylvania Native American history of West Virginia Formative period in the Americas Native American tribes in Maryland Native American tribes in Pennsylvania Native American tribes in Ohio Native American tribes in West Virginia Algonquian ethnonyms Archaeology of the United States Iroquoian peoples Prehistoric cultures in Ohio