Complex sentence: The river enters the Oklahoma Panhandle near Kenton, crosses the southeastern corner of Colorado into Kansas, re-enters the Oklahoma Panhandle, re-enters Kansas, and finally returns to Oklahoma where it joins the Arkansas River at Keystone Reservoir above Tulsa, Oklahoma.
Split into simpler sentences: The river enters the Oklahoma Panhandle near Kenton, then crosses the southeastern corner of Colorado into Kansas. It then re-enters the Oklahoma Panhandle, re-enters Kansas, and finally returns to Oklahoma where it flows into the Arkansas River at Keystone Reservoir above Tulsa, Oklahoma.