This culture group is named for the burials found at Der Tasa, on the east bank of the Nile between Asyut and Akhmim. The Tasian culture group is notable for producing the earliest blacktop-ware, a type of red and brown pottery that is painted black on the top and interior.[40] This pottery is vital to the dating of Predynastic Egypt. Because all dates for the Predynastic period are tenuous at best, WMF Petrie developed a system called Sequence Dating by which the relative date, if not the absolute date, of any given Predynastic site can be ascertained by examining its pottery.