Time, part 3: lists, lists, lists
Dating events and objects is one of the most basic things a historian can do, but that does not mean it is simple. Radiocarbon dating offers no precise dates, but only a possibility that an object dates from a certain age. Dendrochronology is impossible if there is no tree ring sequence available for the area you are studying.
This means that the old methods of establishing a chronology have not been superseded. In turn, this means that unless something is dated according to the common, Christian era (or a similar era), you will have to make use of ancient lists of kings and magistrates.
The main one is the list of Egyptian pharaohs, which sums of the rulers and gives their regnal years. It is not perfect. Because some of the dynasties did not rule after each other, but at the same time, it is too long. These problems were recognized in the nineteenth century and are more or less solved.
However, the problem does return on a smaller scale. Some kings, usually father and son, ruled together. These coregencies are more difficult to recognize and scholars are still trying to finetune the king list. Still, if we read that something happened in this regnal year of that pharaoh, we can make a reasonable guess about the date.
Something similar can be said about the countries of Mesopotamia, where we have several king lists that have been studied since the nineteenth century. Because the Babylonians and Assyrians were obsessed with astronomy, we have accurate dates down to 747 BC. We can go further by using the Assyrian “limmu-list”. The limmu was an official, appointed by the king, who had to organize the New Year festival. This list brings us to 911 BC.
A king list for Assyria, a king list for Babylonia, and a list of contemporary Assyrian and Babylonian kings help us establish the chronology of Mesopotamia down to about 1415 or 1420 BC. Beyond that point, we have older king lists, but there two problems. Firstly, there is often only one copy of a given list, which means that scribal errors cannot be identified and can thus produce grave chronological mistakes. Secondly, there is a gap between 1415/1420 and the youngest king mentioned on the older king lists. This is a dark age of an unspecified length.
Fortunately, we have a tablet with Venus observations from the reign of a Babylonian king named Ammisaduqa. These observations can have taken place in one of four moments only, which means that there are only four possible chronologies, usually referred to as “high”, “middle”, “low”, and “ultra-low”. Last year, German physicist Werner Nahm claimed to have solved the problem (the Middle Chronology is correct), but questions remain.