The paper concerns the problem of periodization of Ancient Russ’s political system formation, and raises the issue of discontinuities between the three historical periods: IX – X centuries, XI – XIII centuries and subsequent time of Moscow Principality. The first historic period of Eastern Europe – from 9th to the mid 10th century – is a time of “military state” (“predatory state») formation. The political system of pre-Mongol Rus’ was made in the mid of 11th century. The next fracture of historic evolution was connected with the crisis of Rus’ and Mongol invasion in 13th century. Besides, the paper raises the question of criterions to compare development rhythms of Medieval Rus’ and Medieval European World.