Origin of the Slavs and their Christianisation

The Slavic peoples constitute a major element in the ethnic make-up of Eurasia and are represented in diaspora communities across the world. In our time Slavs are divided into East Slavs, which includes the Russian people, West Slavs, including, for example, the Poles and Czechs, and the South Slavs, such as the Serbs and Croats. 

The origins of the Slavic peoples, as distinct from the earlier Balto-Slavs, can be traced back to a Urheimat (homeland) which many would locate in Polesia (southern Belarus, but overlapping with Poland, Russia and Ukraine). In historical sources dating back to the first and second century CE, the Slavs are referred to as "Veneti" and/or "Spori". Particularly during the second phase of the Völkerwanderung (Great Migration) around 500 CE, the Slavs, then known as Antes and/or Sklaveni, spread out in all directions. By 518 they were crossing the northern limes (frontier) of the Empire of Constantinople. By the 7th century the whole Balkan area was known as Skalvinia and was inhabited by tribal communities of Slavs known as Sklaveni, Other Slavs spread west, north and east. 

The Christianisation of Slavs by the Eastern Orthodox Church may, arguably, have begun under Emperor Heraclius (r. 610-641), when in 623 Croats and Serbs were settled from what is now Central Europe into their current homelands, however their Christian faith was short-lived. Somewhat later, as the Empire of Constantinople reclaimed areas such as Macedonia and the main Greek peninsula (the "Byzantine Reconquista"), settled by Slavs (and also Avars), these areas were Hellenised, a process, carried out for example under Emperor Nicephorus I (802-811), which included Christianisation. The experience of this missionary work inspired and informed work beyond the borders of the Empire, begun in the 860s: in Bulgaria, and later by Cyril and Methodius and their disciples in Moravia and Pannonia. The Five disciples of Methodius took refuge in Bulgaria, where Clement of Ohrid probably invented the Cyrillic alphabet. It was from Bulgaria that Serbia was evangelised. The work in Kievan Rus enjoyed initial success in 860, but it was the conversion of Princess Olga and later her grandson, Vladimir in 988 that brought Kievan Rus into the orbit of the Eastern Orthodox Church.  

The Slavs were also Christianised by the western Catholic church. The see of Magdeburg was a base for missionary work. For example, Moravia was originally missionised by Frankish missionaries before the Cyril-Methodian mission, and eventually came under the jurisdiction of western church - as did Pannonia. Later, Adalbert of Prague (d. 997) was a leading missionary across eastern Europe. Towards the end of the tenth century various peoples such as the Poles in 966 formally converted to Christianity. Later, in the twelfth century, a missionary crusade was directed against the Wends (a west Slavic people).