Complex sentence: One important event possibly happened during the reign of Khasekhemwy: many Egyptologists read his name ("the Two Powers arise") as commemorating the union of the Upper and Lower Egypts.
Split into simpler sentences: One important event possibly happened during the reign of Khasekhemwy. Many Egyptologists read his name, Khasekhemwy, as "the Two Powers arise"; possibly commemorating the union of the Upper and Lower Egypts.