Serbia, Europe, Historical Profile (1922), #002-History
The Serbs (Srbi, as they call themselves) are a Slavonic nation, ethnically and by language the same as the Croats (Hrvati, Horvati, Croati). The Croats, however, are Roman Catholics and use the Latin alphabet, while the Serbs belong to the Orthodox Church and use the Cyrillic alphabet, augmented by special signs for the special sounds of the Serb language.
The earliest mention of the Serbs is to be found in the ninth century: the origin of the name which appears alike in Lusatia and the Balkans is obscure. Nothing is known of their earlier history except that they lived as an agricultural people in Galicia, near the source of the river Dniester. In the beginning of the 6th century they descended to the shores of the Black Sea. Thence they began to move westerly along the left shore of the Danube, crossed that river and occupied the north-western corner of the Balkan Peninsula.
According to the emperor Constant ine Porphyrogenitus, the emperor Heraclius (610-640) invited the Serbs to settle in the devastated north-western provinces of the Byzantine empire and to defend them against the incursions of the Avars. According to newer investigations, Heraclius only made peace with them, confirming them in the possession of the provinces which they already had occupied, and obtaining from them at the same time the recognition of his suzerainty. Their known history as a Balkan nation begins towards the middle of the 7th century.