Complex sentence: The conflicts between the Powhatan and the ever-expanding English colony decimated the Native Tribes and by the mid 17th century, those remaining had assimilated into other groups, or were living in designated areas along the Pamunkey and Mattaponi Rivers.
Split into simpler sentences: The conflicts between the Powhatan and the ever-expanding English colony decimated the Native Tribes and by the mid- 17th century. Surviving Powhatan assimilated into other Native American groups, or were living in designated areas along the Pamunkey and Mattaponi Rivers.