Ukrainian (formerly known as Little Russian) is an East Slavonic language, closely related to Belarusian (formerly known as Byelorussian, and earlier as White Russian) and Russian; all three use the Cyrillic alphabet. At the time of the Christianization of Rus’ – the East Slavonic territory that stretched from Kyiv (the Ukrainian form of Kiev) in the south to Novgorod in the north – in 988, the East Slavonic group of dialects as a whole was relatively uniform, differing only slightly from region to region. The differences that today separate the three languages from one another were not brought about by internal linguistic change alone; just as important in this regard were events in the realm of political change, mostly in the form of invasions by non-Slavs and annexations by other Slavs.