Ancient European Trees Just Solved a 3,500-Year-Old Cold Case: The Exact Year the Babylonian Empire Collapsed

3 min readMesopotamia in the second millennium B.C.E. left behind an unusually rich written record. Yet historians still can’t agree on exact dates. Rival chronologies hinge on when Babylon fell, and they disagree about that by more than a century, so it’s hard to line up events across the Near East and eastern Mediterranean.Babylon may be best known today from sacred texts, from the Hebrew Bible to the Quran. But long before those books were written, the fabled city on the Euphrates was the capital of one of the ancient world’s great powers. It was home to King Hammurabi, whose law code ranks among the oldest written legal systems on record.On paper, Mesopotamia should be easy to date. Scribes left behind king lists, administrative records, and royal inscriptions that lay out what happened and in what order. The catch is that they counted time by kings’ reigns, not calendar years, so the whole sequence had no fixed link to dates we’d recognize.Venus should have fixed that. Babylonian scribes watched the sky for omens, believing the planets’ movements foretold harvests, wars, and the fate of the king. During the reign of King Ammisaduqa, they wrote down when Venus appeared and disappeared on the horizon, dating each sighting by year of his reign. Because Ammisaduqa also appears in the king lists, those sightings tie the whole sequence of kings to the sky, and modern astronomers can work out when they could have happened.The trouble is that Venus repeats itself, so the observations fit several possible points in history. That left four rival timelines (high, middle, low, and ultra-low) that place Babylon’s fall as much as 150 years apart.The key witness turned out to be wood. Timbers from ancient buildings in Anatolia, in modern-day Turkey, had tree rings that could be lined up in order, but no one could pin that sequence to actual calendar years. Yet those same sites are tied to Mesopotamia through the Old Assyrian trade network, whose merchants left records that line up with Mesopotamian kings. So dating the wood would date the history, too.Now, researchers believe they’ve done just that. In a study published in the journal Proceedings of the National Academy of Sciences, the team wrote that they used “patterns captured in single-year radiocarbon measurements from tree rings to calendar-date Anatolian wood samples from sites with direct archaeological links to Mesopotamia.”Led by Charlotte Pearson of the Laboratory of Tree-Ring Research at the University of Arizona, the team measured carbon-14 in single annual growth rings from the Anatolian timbers. They partnered with ETH Zurich’s Laboratory of Ion Beam Physics to make the measurements.To anchor the Anatolian wood, the team turned to precisely dated Tyrolean stone pine from Austria and oak from Germany. That pinned the Anatolian tree-ring sequence to the calendar, with each ring now tied to a specific year from 2072 to 744 B.C.E. The payoff reaches beyond Mesopotamia. “These data can now be used for samples from anywhere else in the world,” Kurt Nicolussi of the University of Innsbruck told Austria’s public broadcaster, ORF, in a translated report.“Tree-ring dates are combined with archaeological and high-resolution ice-core evidence to evaluate the competing chronological frameworks for Mesopotamia between 2000 and 1500 B.C.E.,” the authors wrote.The verdict: The Old Babylonian Empire fell in 1587 B.C.E. The authors found “strong support” for what they call a middle-low chronology, a timeline that falls between the middle and low models.“This illustrates how high-precision radiocarbon methods, in combination with other interdisciplinary evidence, can enhance chronological accuracy across many time periods,” the authors wrote.Tim Newcomb is a journalist based in the Pacific Northwest. He covers stadiums, sneakers, gear, infrastructure, and more for a variety of publications, including Popular Mechanics. His favorite interviews have included sit-downs with Roger Federer in Switzerland, Kobe Bryant in Los Angeles, and Tinker Hatfield in Portland.