As a researcher he has focused on the Europeanisation process of the Baltic Rim, covering the period AD 750-1500. Already his doctoral thesis awoke some interest among researchers of the Hanse, and he is a member of the Hansischer Geschichtsverein since 1980. By generous support from the Bank of Sweden Tercentenary Foundation he was able to form the multinational and interdisciplinary research project Culture Clash or Compromise, subtitled The Importance of Regional Survival Strategies in the Europeanisation of the Baltic Rim (AD 1100-1400). This so called CCC-project was occupying some 20 scholars – archaeologists, historians and geographers representing seven countries on the Rim and its results are presented in 11 volumes of CCC papers.
For Blomkvist's central contribution to the project, see The Discovery of the Baltic (Brill, The Northern World, Leiden & Boston 2005, 775 pp.). After retirement in 2010, his interests remain the same. From later years a fully commented Swedish translation of Första Novgorod-krönikan (First Novgorod Chronicle) in co-operation with Gun Eile and Gotland museum is to be highlighted (2016), as well as a monography of – “Sveriges första författare” – the Gotlandic 13th-century Dominican friar Petrus de Dacia (Norma 2019).