At the end of May 2000, he published The Formation of the Lithuanian State ("Lietuvos valstybės ištakos"). In the book Baranauskas argued that the Grand Duchy of Lithuania formed earlier than generally accepted; i.e. that the state was founded before King Mindaugas. The book received mixed reviews from academics.
Since 22 June 2000 Baranauskas maintains the largest site on the medieval history of Lithuania on the Internet – "Medieval Lithuania". Since March 2003 he also administers the official website of the Lithuanian Institute of History.
Baranauskas coined the term "Litvinism" for the theory and idea existing in Belarus according to which the Grand Duchy of Lithuania and medieval Lithuanians were Belarusian.[1]