Measuring the distance between events in the stream of time is no new science. Humans have had a general interest in chronology since ancient times. It was a means of explaining to younger generations events that occurred during the days of their forebears and gave coherence to sequences of events and a framework by which a nation or people could understand its true value in history. If the ancient civilizations made no effort to chronicle their histories, this may never have been possible. The Babylonians, and the Assyrians in particular, are noteworthy for their conscientious efforts in this regard. Fortunately, this interest has enabled modern historians to date events of the past. How have present-day chronologists been able to piece together working outlines of Assyrian and Babylonian history from the ancient records?
The earliest evidence we have of dating is in tablets from Sumer. The Sumerian system was to give each year a name, and this name was usually a reference to a significant event that took place in the previous year. Thus, the formula, “year of such-and-such a happening,” actually means, “the first year after that happening.” This system was inherited by the Babylonians, who used it up until the rise of the Kassites. From then on, years were named according to the regnal years of kings.
Every now and then, in the Babylonian system, lists were drawn up of all the year-formulae in a king’s reign. These formulae were then counted, and the number of years that a king reigned could be calculated and recorded. A number of fragments of these lists have been published. Lists covering longer periods were also made, in which dynasties and the length of their terms of power were recorded.
The chief tools for reconstructing Assyrian chronology are the recordings of the eponyms or limus, as the Assyrians called them. A limu was a title assumed by a high royal official each year. That official’s name was chosen as the name of the year in which he received the honor of eponym. The king would receive this privilege at least once during his reign and usually at the beginning. Thus, instead of using numbers to designate specific years, or naming years after certain events as the Babylonians and earlier Mesopotamians did, the Assyrians year-names were the names of actual political personalities. They would dedicate each year to an official, and over time they would compile long lists of these eponyms to keep track of their history.
In modern times, many of these lists have been discovered archaeologically. There are two types: 1) eponym lists and 2) eponym chronicles. The lists merely recount the name of each limu in order. One of the lists includes the titles of the officials as well. The chronicles, on the other hand, include an event that occurred in each particular year. Assyriologists designate the lists as class A sources and the chronicles as class B.
The surviving eponym records are actually copies made in the seventh-century B.C.E. from older sources, and there are unfortunately numerous discrepancies between various copies. However, by comparing their contents, scholars have been able to make fairly trustworthy determinations with respect to all but minor details.
As a means of calculating the reigns of Assyrian rulers, the eponyms are invaluable. Apparently on many copies, certain ancient scribes made horizontal rulings between the reign of each king so that we are able to determine when each of these monarchs came to power. It has become clear that each king traditionally held the office of eponym during his second full year of reigning up until the time of Shalmaneser V, when he and his successors broke that pattern. If a king reigned over thirty years, he could receive the eponym a second time.
The problem is, although the eponyms are extremely helpful, they are what is called a “floating chronology.” In other words, we may know the length of kings’ reigns from the lists, but if we truly wish to reconstruct a history, we must be able to equate certain events with real dates. Fortunately, a way has been found to anchor this floating chronology to a time line.
Recorded in the eponym of a certain official named Bur-Sagale is an event for which we can provide a date. It reads “simani šamaš attalu ištakan“, which translates, “in the month Siwan, the sun had an eclipse.” There is no doubt that the word attalu means eclipse, as it is attested in other documents. It is quite a simple matter, in this age of computers, to calculate the date of any solar eclipse that occurred around that time and that could be seen from that location. The book Solar and Lunar Eclipses of the Near East provides a complete list of eclipses that could have been seen from Nineveh between 1511 and 490 B.C.E. Of course, one need not search the entire list, as it can be estimated that Bur-Sagale probably lived in the eighth or ninth century. Most scholars have agreed that the eclipse that took place on June 15, 763 B.C.E. is the one that best fits the description of the eponym chronicle. (Another candidate might be one on June 13, 809 B.C.E.) With this anchor point, each limu in the entire eponym canon can be assigned a specific date, and, with the information available, the reigns of kings who ruled between 910 to 649 B.C.E. can be determined.
A connected list of eponyms for the years 649 B.C.E. until the fall of Nineveh does not presently exist. Although there are eponyms, they are not part of the lists and are thus called post-canonical. According to Babylonian chrononlogy, Nineveh fell in 612 B.C.E., therefore 37 eponyms should exist for this period. However, the number of attested post-canonical eponyms is 50. Scholars’ solutions for this discrepancy are numerous. One explanation is that some of these eponyms are from after the fall of the empire. Another is that there are repetitions or mistakes. The most probable solution is that there were a number of eponyms in use in different cities. What would the reasons be? 1) that there were always eponyms in use in various cities, but these have not survived (except perhaps in the variants of class A lists), and 2) that the destruction of the centrality of the empire resulted in several cities picking up the practice in order to maintain some sort of cultural identity. This theory, however, cannot as yet be proven.
This dark period incorporates the reigns of three monarchs: Ashurbanipal (his final years), Ashur-etil-ilani, and Sin-shar-ishkun. The precise lengths of their reigns is not known; however, we know from certain business documents of the time that Ashur-etil-ilani sat on the throne for at least four years and eight months, and Sin-shar-ishkun for seven. The date for the death (or abdication) of Ashurbanipal seems to fluctuate. In various books I’ve seen it given as 625, 626, 627, and 631. His annals break off at 639 B.C.E., and there is attestation of a thirty-eighth year (631), but that is all we know. One later inscription credits him with a reign of 42 years, thus making his last year 627, but whether this is a reliable figure is disputed.
For the period immediately prior to 910 B.C.E., a list of limus is available from various stelae found at Ashur. These provide us with lengths of reigns back to Ashur-uballit I (1362-1327 B.C.E.) in the Middle Assyrian period, but there is certain amount of conjecture. Before this time dates are highly speculative, but we do have some indications as to the placement of certain kings in the stream of time.
For example, Shalmaneser I (1272-1243 B.C.E.) is said to have reckoned 580 years from the beginning of King Erishum’s reign to his own. This would place Erishum’s accession year circa 1852. Shalmaneser also relates that the time from Erishum to Shamshi-Adad I was 159 years. (This number probably included Shamshi-Adad’s reign.) Thus Shamshi-Adad is reckoned as ending his rule circa 1693. However, Tukulti-Ninurta I (1242-1206 B.C.E.) contradicts these figures by saying that 720 years had passed from the beginning of King Ilushuma’s reign (he was Erishum’s predecessor) until his own. With the assumption that Ilushuma reigned 22 years, it would seem that Tukulti-Ninurta was off by 89 years. Apparently he had in his possession another version of the king-list with 89 additional years to it. Scholars are willing to side with his account, as it appears the standard version of the king-list has some omissions. This being the case, the year assigned for the death of Shamshi-Adad I is 1783 B.C.E.
Another document of great assistance in calculating dates for the reigns of Assyrian and Babylonian kings is the Synchronistic History. It is a concise narration of relations between Assyria and Babylon stretching from the reign of Puzur-Ashur III to the reign of Adad-nerari III. As a historical document the Synchronistic History is somewhat unreliable, but its value for chronological calculations cannot be understated, as it relates which Assyrian and Babylonian kings were contemporaries. Thus, Babylonian chronology can now come to the aid of Assyrian, and vice versa. Likewise, a similar document called the Synchronistic Chronicle makes correlations of this sort. It is badly damaged, but many more Assyrian and Babylonian contemporaries are listed.
These are the chief tools we have at our disposal when piecing together Mesopotamian history. To be sure, there are other minor helps from some other sources that have proved valuable, such as other fragments that make certain synchronisms between Assyrian and Babylonian kings, data from contracts, and time references in building foundations. However the Assyrian eponyms, and the Synchronistic History and Chronicle are the foundation of Mesopotamian chronology. We can only hope that more helpful information will come to light in the near future.
 F. Thureau-Dangin, La Chronologie de la Premiere Dynastie Babylonienne (Academie des Inscriptions et Belles Lettres 43, 1940), 220.
 Ungnad and Ebeling, Reallexikon der Assyriologie (Zweiter Band, 1935-36), 131-196.
 A. K. Grayson, Assyrian and Babylonian Chronicles (Locust Valley, New York: J.J. Augustin, 1975), 196.
 Millard, Alan, The Eponyms of the Assyrian Empire 910-612 B.C. (Helsinki: Neo-Assyrian Corpus Project, 1994), 4-5.
 Millard, 12-14.
 Millard, 41, 58.
 CAD A, pt. 2, 505-509.
 M. Kudlek and E. H. Mickler, Solar and Lunar Eclipses in the Near East (Alter Orient und Altes Testament I, Kevelaer-Neukirchen-Vluyn, 1971), 35-41.
 Millard, 72-73; J. Oates, “The Fall of Assyria (635-609 B.C.)” in Cambridge Ancient History, vol III, part 2 (Cambridge: Cambridge UP, 1991), 164.
 A. T. Olmstead, History of Assyria (Chicago: University of Chicago Press, 1960), 628; C. J. Gadd, The Fall of Nineveh (London: Oxford UP, 1923), 4.
 J. Oates, 162-171.
 H. Lewy, “Assyria, c.2600 – 1816 B.C.” in Cambridge Ancient History, vol I, part 2; 3rd ed. (Cambridge: Cambridge UP, 1971), 743; S. Smith, Early History of Assyria (New York: E.P. Dutton and Company, 1927), 345-47.
 Lewy, 750-51.
 Grayson, 51-56.
 ANET, 272-73.
 P. van der Meer, The Chronology of Ancient Western Asia and Egypt, 2nd ed. (Leiden: Brill, 1963), 39.