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. 2016 Jul 13;11(7):e0157144.
doi: 10.1371/journal.pone.0157144. eCollection 2016.

Integrated Tree-Ring-Radiocarbon High-Resolution Timeframe to Resolve Earlier Second Millennium BCE Mesopotamian Chronology

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Integrated Tree-Ring-Radiocarbon High-Resolution Timeframe to Resolve Earlier Second Millennium BCE Mesopotamian Chronology

Sturt W Manning et al. PLoS One. .
Free PMC article


500 years of ancient Near Eastern history from the earlier second millennium BCE, including such pivotal figures as Hammurabi of Babylon, Šamši-Adad I (who conquered Aššur) and Zimrilim of Mari, has long floated in calendar time subject to rival chronological schemes up to 150+ years apart. Texts preserved on clay tablets provide much information, including some astronomical references, but despite 100+ years of scholarly effort, chronological resolution has proved impossible. Documents linked with specific Assyrian officials and rulers have been found and associated with archaeological wood samples at Kültepe and Acemhöyük in Turkey, and offer the potential to resolve this long-running problem. Here we show that previous work using tree-ring dating to place these timbers in absolute time has fundamental problems with key dendrochronological crossdates due to small sample numbers in overlapping years and insufficient critical assessment. To address, we have integrated secure dendrochronological sequences directly with radiocarbon (14C) measurements to achieve tightly resolved absolute (calendar) chronological associations and identify the secure links of this tree-ring chronology with the archaeological-historical evidence. The revised tree-ring-sequenced 14C time-series for Kültepe and Acemhöyük is compatible only with the so-called Middle Chronology and not with the rival High, Low or New Chronologies. This finding provides a robust resolution to a century of uncertainty in Mesopotamian chronology and scholarship, and a secure basis for construction of a coherent timeframe and history across the Near East and East Mediterranean in the earlier second millennium BCE. Our re-dating also affects an unusual tree-ring growth anomaly in wood from Porsuk, Turkey, previously tentatively associated with the Minoan eruption of the Santorini volcano. This tree-ring growth anomaly is now directly dated ~1681-1673 BCE (68.2% highest posterior density range), ~20 years earlier than previous assessments, indicating that it likely has no association with the subsequent Santorini volcanic eruption.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.


Fig 1
Fig 1. An example of an Old Assyrian clay tablet text: Yale Babylonian Collection, NBC 1905, showing a sealed Old Assyrian legal record.
Fig 2
Fig 2. Locations of Anatolian sites with tree-ring chronologies analyzed and discussed in this paper.
Fig 3
Fig 3. Site tree-ring chronology composition, showing sample numbers/depth and their relative positions according to the previously proposed dendrochronological placements [23] and a summary of the crossdating statistics (tBP) from the TSAP software [37] (other crossdating statistics are available in S1 File).
Fig 4
Fig 4. Comparison of the 14C data on each set of Juniperus spp. tree-rings from each site.
Errors bars show 95.4% probability ranges. In all but one case, OxA-30897 & OxA-31521 from MBA relative rings (RY) 677–685, the data on the identical tree-rings are compatible to be combined as weighted averages to give the best available estimates of the appropriate 14C age [60]. Dates on the same or similar (site or time interval) tree-rings measured at different laboratories also show good agreement.
Fig 5
Fig 5. 14C measurements from the tree-ring time-series excluding outliers as best placed against the IntCal13 14C calibration dataset (modelled and raw data) [–63].
Plot shows data and placements from Models 3, 6, 8a in Table 2 (see also Figures J-N in S1 File). Inset shows the alternative placement for the Gordion series if only Gordion RY 776.5 to 1145.5 are employed [40], i.e., Model 5 versus Model 3 placement (see Table 2) (see Section C in S1 File).
Fig 6
Fig 6. We test the previously published Anatolian dendrochronological placements [–23, 31, 40] by independently dating the MBA, POR and GOR chronologies and calculating the calendar age range for what should–if the previous placements were correct–be exactly the same date.
We choose to test the previously published placements versus the major RY 854 tree-ring growth anomaly observed in the Porsuk chronology (this is an arbitrary choice but of relevance to the supposed Thera/Santorini association [46]). Differences between the dendro-14C-wiggle-match placements of the various time-series (see Fig 5) are shown in terms of the overall calculated probability distributions (marginal posterior densities) for the calendar age placement for RY 854 (note: the tree-ring series do not all include an RY854 –this year is extrapolated in such cases to enable the comparison in terms of a single year). The 68.2% and 95.4% highest posterior density (hpd) ranges, along with the μ±σ and the median, are also indicated.
Fig 7
Fig 7. The relative and approximate absolute calendar placements of the MBA, Porsuk and Gordion tree-ring series in Fig 3 revised according to the tree-ring-14C dates reported in Table 2 and with no dendrochronological crossdate connection between the Porsuk chronology and either the Gordion or MBA chronologies.
Inset: the tBP crossdate values calculated from TSAP [37] for the constituents of the MBA chronology. There is no tree-ring-based link with either Porsuk or Gordion.
Fig 8
Fig 8. Comparison of the proposed calendar dates BCE from some of the main Mesopotamian Historical Chronologies [, –19, 73] for four key REL dates [5] versus the dendro-14C-wigglematch date ranges (95.4% probability range) for the likely Earliest Use (EU) of the Sarıkaya Palace at Acemhöyük [23] as +1 year from latest primary construction timber with bark/waney edge (data from Table 2, Model 8a, Table 3), and including the subsequent dendrochronologically known repairs/additions to the building [23].
The known lifetime of the Sarıkaya Palace runs from the time of Šamši-Adad I (with nothing earlier) through sealings of Aplahanda of Carchemish who died around REL 208. The dates indicated are: (i) REL 165 (Šamši-Adad I conquers Aššur); (ii) REL 197 (death of Šamši-Adad I) [5]; (iii) REL 190s which represent a cluster of dates on documents at the Sarıkaya Palace [29]; and (iv) REL 208. The respective calendar dates BCE for the Fall of Babylon (sacked by the Hittite king Muršili I) according to the five main Mesopotamian Historical Chronologies [, –, –19, 73] are given in green text also (note: the chronology of Mebert [19], 8-years later than the Low Chronology, is not shown).
Fig 9
Fig 9. Fig 8 modified by adding the Earliest Use (EU) date range (95.4% probability) and repairs/additions for the Waršama Palace at Kültepe, and adding the calendar date (BCE) for REL 141 (last year before Kültepe Lower Town Level Ib is attested in use) [5] on the basis of some of the main Mesopotamian Historical Chronologies [, –, –19] (Note: the chronology of Mebert [19], 8-years later than the Low Chronology, is not shown).
The attested REL dates (80–110) or likely approximate terminus ante quem (TAQ) REL date (~REL 125) from Old Palace contexts prior to the construction of the Waršama Palace ([5] at p.31) are also indicated.

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    1. Charpin D, Edzard DO, Stol M. Mesopotamien Die altbabylonische Zeit. Göttingen: Academic Press, Fribourg/Vandenhoeck & Ruprecht; 2004.
    1. Veenhof KR, Eidem J. Mesopotamia The Old Assyrian Period. Göttingen: Academic Press, Fribourg/Vandenhoeck & Ruprecht; 2008.
    1. Barjamovic G. A historical geography of Anatolia in the Old Assyrian colony period Copenhagen: Museum Tusculanum Press; 2011.
    1. Larsen MT. Ancient Kanesh: A Merchant Colony in Bronze Age Anatolia. New York: Cambridge University Press; 2015.
    1. Barjamovic G, Hertel T, Larsen MT. Ups and Downs at Kanesh–Observations on Chronology, History and Society in the Old Assyrian period. Leiden: Nederlands Instituut voor het Nabije Oosten; 2012

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Grant support

This work was supported by the National Science Foundation, BCS 1219315, (SWM); Social Science and Humanities Research Council, Canada,, via CRANE project, (SWM); and Malcolm H. Wiener Foundation (SWM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.