At the beginning of the 20th century, he was one of the founders of East German research and advocated dealing with the Eastern European states amicably.
In 1899 he obtained a PhD, worked for several newspapers and was active in the Alldeutscher Verband and favoured the creation of a German Navy.
Between 1923 and 1934 he repeatedly travelled to the Soviet Union and founded the Journal Osteuropa (Eastern Europe) which still exists.
Although he was a German nationalist (like many of his contemporaries in 1914 he had enthusiastically welcomed the outbreak of World War I), the Nazis considered him a Bolshevik.
In 1966 his classic text Grundzüge der Geschichte Russlands was translated and published as The Evolution of Russia as part of the "Library of European Civilization" series.