In the archaeology of part-literate societies, dating may be said to operate on two levels: the absolute exactness found in political history or 'history event-by-event', and the less precise or relative chronology, as found in social and economic history, where life can be seen to change with less precision over time.
So in the absence of geochronology, two cultural groups can only be proved contemporary by the discovery of links between them.
For a long period in the 20th century Egyptian and Near Eastern chronology seemed to be the earliest of absolute chronologies, and imports from these areas were used to reconstruct the chronology of European prehistory.
With the introduction of objective quantifiable methods such as dendrochronology and Carbon-14 dating, over the past half century, European and North American archaeology have developed independent and more reliable chronologies, that often make it possible to date more precisely than in Egypt. For Egypt absolute year dates can only be established back to the beginning of the Late Period, from links to Greek chronology, and then from Assyrian king-lists and other Near Eastern sources, back to the Ramesside Period (still debated). The Egyptians dated by the year of reign of the king on the throne (for example 'year 3 of king X').
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.