Ask most people, including Russians, who have a modest familiarity with European history what they know about medieval Russia and their answer will probably be brief, but will include something about the Mongols, perhaps even 'the Tatar yoke' (for a succinct statement of the difference between Mongols and Tatars see Ostrowski's preface, p. xiii).
Many scholars have thought to write a full presentation of the relations between the Catholic West and the Mongol Empire during the Middle Ages. It is a demanding task. The author should be specialised in many areas, know many languages, and he or she has to fit his or her presentation into a world historical context.
What is a ‘Companion’ for?