Politics is the study of decision-making power (who's got it, and who hasn't). Politics can take many forms -- discussions, arguments, etc.
Some of the things that need covering in a discussion of medieval through to early modern politics include: Roman conquests, neo-Roman (eg: romano-british) activity, Viking activity, the Church, Aryanism and Catholicism, Charlemagne, the Pope, the Empire, the Church again, the Gothic, Vandal, Magyar, Hunnish, Khazar, Mongol and Gothic (again) invasions and settlements, the Eastern Orthodox church, the schisms, the other schisms, early nationalism (which bears no resemblance to post-18th Century nationalism), the Danelaw, the Roman law and interpretations of Roman law, secular and temporal law, the Empire again, Papal authority and excommunication, Crusades and Jihad, the Latin states, the schism again, the city state, Catholicism and the Muslim view of the Frankish world, the Catholic view of the Muslim world, anti-papal reformations, the nationalist churches, the city states again, the reformation and protestantism, Niccolo Machiavelli, Castiglione, Mary I and Elizabeth I, the foundation of the papal and catholic plots against Elizabeth, 1588 and the armada, and at about that point we run out of time.
Oh, and in no particular order.
Politics in the SCA
Politics in the SCA usually revolves around the officers and peers of the SCA, not to mention the Crown. Fortunately, in the case of the latter, we have a system that is very similar to the system in place in the early Middle Ages in that the strongest person with the largest (in our case blunt) sword is the winner.