If we knew the precise length of reign for every Egyptian king, chronology would be no problem.However, we do not even know the number of kings for all periods, and there is also the possibility that reigns overlapped by coregency or in times of political disunity.
The main surviving kinglists from ancient Egypt beside the 'Palermo Stone' are hieroglyphic inscriptions of Thutmose III (Karnak, probably a list of statues displaced in temple construction), Sety I and Ramses II (both at Abydos), and a fragmentary hieratic manuscript from Thebes (Turin Canon).
Kinglists in Greek, apparently compiled by a third century BC Egyptian priest named Manetho, are preserved in summaries by early Christian writers, with excerpts in other writers of the Roman Period and later, notably the Jewish historian Josephus.
The annual rings vary in size, depending on the weather conditions in each region, but they are similar for all trees of the same area.
If the sequence of rings is know for a certain area it is possible to fit in all new woods found and to date them very precisely.
In Egyptology the method was first used by Petrie for dating the Naqada period, from the development of the so-called wavy-handled pottery.