The Arvilla Complex is primarily defined by burials distributed across central Minnesota, the Red River Valley and its tributaries in Minnesota, North Dakota and Manitoba. Artifacts and skeletal material in the sites dates from 500 to 600 AD. The Complex disappeared in the southern part of its range by 900 AD. It may have persisted for several centuries longer in the North.
The Complex is characterized by both linear and circular mounds with extended or flexed complete and disarticulated primary burials, bundled secondary burials frequently associated with red and yellow ochre. The burials are placed in pits dug under the associated mounds. Burial goods include marine shell, bone, and antler ornaments, bone and antler utilitarian objects, and pottery elbow pipes. Chipped stone tools are less common than bone and antler and pottery vessels are rare. Artifacts are primarily northern with an intrusion of marine shell trade goods of southern origin.