Palermo Stone
Although the Egyptian priest Manetho, writing in the third century BC, stated that Djer ruled for 57 years, modern research by Toby Wilkinson in "Royal Annals of Ancient Egypt" stresses that the near-contemporary and therefore, more accurate Palermo Stone ascribes Djer a reign of "41 complete and partial years." Wilkinson notes that years 1–10 of Djer's reign are preserved in register II of the Palermo Stone, while the middle years of this pharaoh's reign are recorded in register II of Cairo stone fragment C1.