SUMMARY Tephra-linked pollen diagrams from lowland raised peats at three sites in the north of Ireland show extensive landscape changes between A.D. 750 and A.D. 1150. By A.D. 860 woodland had been cleared and agricultural activity was widespread but, by the start of the twelfth century, woods had regenerated and agriculture had declined. The gap in the Irish dendrochronological record between A.D. 730 and A.D. 850 is bridged by timbers from corn grinding mills, strengthening the case for spreading arable agriculture at this time.