This volume presents the results of diachronic archaeological and palaeoecological research conducted in two study areas: the intermontane Kazanlak Valley along the Upper Tundzha River of central Bulgaria, and the Thracian Plain along the Middle Tundzha River south of the city of Yambol in southeastern Bulgaria. The Tundzha Regional Archaeology Project (TRAP), a cooperative effort including Australian, Bulgarian, and Czech investigators, undertook archaeological survey and environmental sampling between 2009-2011. Major field activities of the project included over 100 sq km of systematic pedestrian survey, legacy data verification and mapping, trial excavations, artefact processing, and environmental sampling in and around the study areas. Through this research, TRAP inventoried over 100 surface artefact concentrations and 800 burial mounds. At the heart of the volume is a geospatial analysis of settlement patterns derived from the survey dataset, which relates the footprint of past human activities to environmental and sociocultural drivers. We also present a range of associated studies conducted between 2009-2015: histories of archaeological research in both study areas, soil erosion and productivity modelling in the Kazanlak Valley, reconstruction of a 30,000-year environmental history based on samples from a wetland in the Thracian Plain north of Yambol, investigation of palaeodiet using isotope analysis of human remains from Bronze Age burials in the Yambol study area, exploration of shifting Roman occupation patterns based on trial excavations in the Yambol area, research into subsistence strategies based on palaeobotanical evidence recovered from one of the Yambol area trial excavations, analysis of trade and exchange based on the transport amphorae fragments recovered during Yambol-area survey, and epigraphic comparison and synthesis of Classical, Hellenistic, and Roman inscriptions from the two study areas. Finally, TRAP has produced a granular digital dataset of surface artefacts and features unparalleled in Bulgaria to promote reinterpretation of our results, encourage secondary studies, and foster comparative research.