Gil, I.M., Abrantes, F. and Hebbeln, D. 2006. The North Atlantic Oscillation forcing through the last 2000 years: Spatial variability as revealed by high-resolution marine diatom records from N and SW Europe. Marine Micropaleontology 60: 113-129.
Working at two sites along the European margin of the North Atlantic -- in the Skagerrak (about 58°N, 9.5°E) and the Tagus pro-delta (about 38°35'N, 9°W) -- and based on diatom and phytolith data obtained from marine sediment cores retrieved therefrom, Gil et al. reconstructed 2000-year histories of environmental changes at both locations. And in describing their results, the three researchers state that their efforts revealed "a similar timing for environmental changes off the Tagus River and at Skagerrak through the last 2000 years, with the Dark Ages [Cold Period] occurring between AD 400 and 650, the Medieval Warm Period between AD 800 and 1200 and the Little Ice Age between AD 1350 and 1900." Thus, we conclude from their research that the MWP did indeed manifest itself in the two locations over the common time period of AD 800-1200.