4,000-Year-Old Sealed Cuneiform Letters from Anatolia Read Without Breaking Their Clay Envelopes

4,000-year-old sealed cuneiform letters from ancient Anatolia have been read without breaking their clay envelopes, thanks to a mobile X-ray CT scanner designed to bring advanced imaging directly into museum collections.

The study, published in npj Heritage Science, marks an important step for Assyriology and cultural heritage science. Many cuneiform tablets from Southwest Asia remain sealed inside clay envelopes, making their texts inaccessible unless the outer shell is destroyed. For decades, that was the only way to read them. It also meant losing seal impressions and other traces left by the people who sent, handled, and protected the documents.

A portable scanner for ancient letters

The new scanner, called ENCI, short for Extracting Non-destructively Cuneiform Inscriptions, was developed by an interdisciplinary team led by Assyriologist Cécile Michel and X-ray physicist Christian G. Schroer, with specialists from the University of Hamburg and DESY in Germany.

Unlike large stationary tomography systems, ENCI was built to travel. The full device weighs about 420 kilograms and can be taken apart into eight components. Once assembled inside a museum, it can scan a sealed tablet in minutes, creating a high-resolution 3D model that allows researchers to virtually separate the hidden tablet from its clay envelope.

The scanner was first tested at the Louvre Museum in Paris in 2024. It was later taken to the Museum of Anatolian Civilisations in Ankara, where researchers recorded 64 tomograms of 48 tablets and other objects over a three-week campaign.

Letters from Kültepe’s Assyrian merchants

Many of the scanned objects come from Kültepe, ancient Kanesh, in central Anatolia. In the 19th and 18th centuries BC, Assyrian merchants from the city of Assur lived and worked there, managing long-distance trade in textiles, silver and other goods.

Their letters were written on small clay tablets and then sealed in clay envelopes. On the outside, only the names of the sender and recipient were usually written, together with seal impressions. The real message remained private until the envelope was broken.

One of the most revealing examples is a letter sent by Anna-anna to her husband Ennum-Aššur. The envelope showed only her seal and his name. Inside, however, the newly readable text tells a more personal and practical story. Anna-anna had been trying to recover silver owed to her absent husband, but the debtor refused to pay her directly, saying he would return the money only when Ennum-Aššur came back.

The letter is valuable because it shows women in Old Assyrian merchant households not as passive figures, but as people involved in business affairs when men were away on trade journeys.

More than hidden words

Another sealed letter revealed that ancient scribes sometimes used a second small clay tablet as an extra page when the main tablet was not enough. This particular message dealt with textiles, donkeys and commercial arrangements, offering a direct view of the mechanics of long-distance trade.

The scans also exposed details that could not be seen from the outside. Researchers could identify clay layers, inclusions, possible organic traces and the way envelopes were folded around tablets. The results suggest that many envelopes were not made from a single clay sheet but from several layers, likely making them stronger for transport.

For archaeology, the real significance lies in what may now become readable for the first time. Sealed tablets were never meant to survive as closed objects; most remained intact only because they were lost, undelivered or left behind in ancient archives.

ENCI turns these unopened letters into historical witnesses without sacrificing their envelopes, seals or traces of manufacture. In the case of Kültepe, that means not only recovering words hidden for 4,000 years, but also hearing the practical concerns of merchants, families and women such as Anna-anna, who managed business matters while men travelled across Anatolia’s trade routes.

The technology may now give museums a way to open some of the world’s oldest private correspondence without physically opening it at all.

Michel, C., Schroer, C.G., Olbrich, S. et al. Deciphering 4000-year-old cuneiform letters hidden in clay envelopes using a mobile X-ray computed tomography scanner. npj Herit. Sci. 14, 303 (2026). https://doi.org/10.1038/s40494-026-02568-7

Cover Image Credit: Letter Kt 94/k 1150 from the Museum of Anatolian Civilisations in Ankara. Credit: Michel, C., et. al., 2026