From this Williams concluded that "Egypt and Nubia A-Group culture shared the same official culture", "participated in the most complex dynastic developments", and "Nubia and Egypt were both part of the great East African substratum".[122] Williams also wrote that Qustul in Nubia "could well have been the seat of Egypt's founding dynasty".[123][124] Diop used this as further evidence in support of his Black Egyptian hypothesis.[125] David O'Connor wrote that the Qustul incense burner provides evidence that the A-group Nubian culture in Qustul marked the "pivotal change" from predynastic to dynastic "Egyptian monumental art".[126]