Assessing the impact of past human activity on landscape change in the Mediterranean has always presented challenges, requiring sound chronological frameworks for observed environmental change. The current research, focused on the environs surrounding the ancient city of Butrint (southern Albania) during Late Antiquity, c. 4th–6th Century AD, establishes a tephra-based chronology for landscape change through the discovery of ash horizons from a little known eruption on the island of Lipari (Aeolian Islands). Recovered glass shards were geochemically fingerprinted to a 6th Century AD event on the island, dated through local archaeological sequences and corroborated by hagiographic evidence. The presence of this marker horizon at Butrint shows a continuation of open water, estuarine conditions throughout Late Antiquity and the Early Medieval period (during which time Butrint ceases to function as an urban centre), disproving the widely held notion of increased soil erosion/deposition as a result of post-Roman landscape degradation. The study also shows that it is following the medieval revival of the town in the 13th Century that marked environmental change takes place, as estuarine areas silt, giving rise to marsh and wetland. The study highlights the importance of using a range of dating techniques to constrain landscape change, while the presence of the 6th Century Lipari tephra in Epirus, derived from an eruptive event larger than previously suspected, provides a useful regional dating marker for future landscape studies.