The subject for this symposium may seem at first glance to be rather technical, and perhaps even antiquarian. But for anyone who has attempted to do research and writing, not to mention serious reading, about the part of Eastern Europe we deal with here will know that periodization and terminology are basic. Without a generally agreed—upon conception of them, one cannot produce an understandable historical narrative, much less a viable interpretation. Without such a common conception, the writing of history is like a game in which the opposing players and referees are all playing under different rules.