Dataset description This dataset contains dendrochronological data from Roman period archaeological sites across Europe. The dataset comprises the description of tree-ring series from 20,397 individual wood samples, and associated metadata documenting geographic, chronological, biological, and archaeological characteristics. The description, analysis and interpretation of this dataset is published as: Muigg B., Haneca K., Tegel W., Grünewald M., Bernard V., Bleicher N., Blondel F., Bolliger M., Broich M., Couturier Y., van Daalen S., Domínguez-Delmás M., Girardclos O., Herzig F., Langenegger F., Digol Y.L., Nelle O., Nicolussi K., Oberhänsli M., Perrault C., Rzepecki A., Vorst Y., Weidemüller J., Westphal T. & Seim A. 2025: Woodlands of Antiquity: A millennium of dendrochronological data on forest exploitation and timber economy between the Alps and the Atlantic, PNAS 122 (48) e2516240122. https://doi.org/10.1073/pnas.2516240122 Geographic Coverage The dataset consists of tree-ring data from archaeological sites across 7 countries: Germany, France, The Netherlands, Belgium, Luxembourg, Switzerland and Austria. Temporal Coverage The dataset primarily covers the Roman period, with absolutely dated tree-ring series ranging from 300 BCE and 700 CE, though individual samples may extend this range. Data Collection The data were compiled from multiple dendrochronological laboratories and research projects across Europe, representing collaborative efforts to document Roman period timber use and forest management practices. Data Structure The dataset contains 23 variables organized into the following categories: Geographic Variables `country`: Modern country where sample was collected `administrative_unit`: Administrative region within country `location`: Specific site location identifier `latitude`: Decimal degrees latitude (WGS84) `longitude`: Decimal degrees longitude (WGS84) `roman_province`: Historical Roman province designation `study_region`: Research-defined regional grouping Laboratory and Sample Information `project_lab`: Laboratory or institution responsible for analysis `series`: Unique sample/series identifier `taxon`: Tree species (primarily Quercus - oak species) Dendrochronological Data `series_length`: Number of tree rings measured `start_date`: First year of tree-ring series (negative values = BCE) `end_date`: Last year of tree-ring series (negative values = BCE) `pith`: Presence of pith center ("yes"/"no") `sapwood`: Presence of sapwood ("yes"/"no") `n_sapwood`: Number of sapwood rings present `waneyedge`: Presence of bark edge/waney edge ("yes"/"no"/"H/S border" = heartwood-sapwood transition) `felling_date_type`: Precision of felling date estimate "exact felling date": Waney edge or complete sapwood preserved, allowing precise dating "felling date interval": Sapwood partially preserved, allowing to estimate a date range for the actual felling date "post quem date": Minimum possible felling date when outer rings are missing Archaeological Context `object_type_10`: Primary object category (10 categories) - Dwelling/settlement - Industry - Military infrastructure - Transport infrastructure - Religious structure - Water well - Watercraft (ship/log boat) - Watermill - Waterfront/water structure - Other water infrastructure `element_type_15`: Specific timber element type (15 categories, e.g. "plank", "beam", "pile/stake", etc.) `element_type_3`: Broad element classification (3 categories, "timber", "small object", "wooden container") `settlement_status`: Settlement type (civil/military/religious/other) `settlement_scale`: Settlement size (rural/urban) Data Quality and Completeness Notes: Not all variables are complete for every sample; `NA` values indicate missing or not applicable data. Felling date precision varies by sample preservation and analytical methods. Geographic coverage is uneven across the study region. Attribution When using this dataset, please cite the associated publication (Muigg et al. 2025), this Zendodo record, and acknowledge the contributing laboratories listed in the `project_lab` variable.

Changes in version 2 Reassigned the `project_lab` attribution for 2,896 records from "DLWF – Dendrolabor Westphal Frankfurt (DE)" to "BLFD – Dendrochronologisches Labor Thierhaupten (DE). Refined the roman_province and study_region attributes for 57 records across 10 find locations (e.g., correcting "Germania Magna (outside Limes)" to "Germania Superior"). Updated the dataset distribution map to fix a legend error where color codes were transposed for study_region (Region SE and SW). The map now correctly aligns with the categorical metadata.