About the book: 2011 / Relations between the two Slavic peoples over the last millennium have been complex and sometimes dramatic. In the 10th–13th centuries, Russian and Polish princes actively collaborated: traded, created military alliances. Most of the Polish princesses were from the Rurik family. There were also wars, but not between peoples, but between princes: one called another, a Lyakh or a Rus, against the third. Subsequently, however, the intervention of the Catholic Church and the arbitrariness of the Polish magnates divided the two peoples. In the 19th and 20th centuries, attempts were made repeatedly to reconcile them. Mutually beneficial cooperation was established for decades, but, alas, there were always forces that made us forget about our common Slavic roots.