Who even are the Slavs?

Slavs are an ethnic and linguistic grouping inhabiting most of eastern Europe and parts of western Europe and Asia, forming the majority in 13 countries and existing as an indigenous minority in three others; the amount of Slavic ethnic groups and languages spoken is much larger than this, though it is hard to specify the exact numbers and borders due to the similarities between the groups and disagreements in academia. Nonetheless, they can be divided into three main groupings:

1. Western Slavs, with the major nations of Czechs, Slovaks, Poles and Sorbs, though other groups such as with various degrees of self-identification and state recognition also exist, most notably Silesians, Kashubians and Moravians
2. Eastern Slavs, mainly comprising of Belarusians, Rusyns, Ukrainians and Russians; the last in particular can be further split into northern and southern Russians. Beyond this, several minority groups can be found, such as Pomors or the different Cossack hosts
3. Southern Slavs, which can be further divided into western (including Slovenes, Croats, Serbs, Bosniaks, Montenegrins and others) and eastern (majorly Bulgarians and Macedonians) subgroups. Unlike the others mentioned, much of the western subgroup (with the exception of Slovenes) is primarily defined by religion rather than language.

The exact homeland of Slavic people is unknown, though most scholars place it between the northeastern foots of the Carpathian mountains and the area of Polesia. Besides their closeness to Balts, the other cultures of the area played a large role in the shaping of the religion, in particular Scythians, Ugro-Finnic people, Goths and Huns. On the other hand, the barrier of the mountains limited Slavic contact with the Romans and other people around the Medditeranean, which kept them away from the religious influences of the empire, but also reliable historical records. Thus, the vast majority of what is known comes from after the 5th century, when Slavic tribes began to migrate outwards.

Sources

Zelenin, Dmitry Konstantinovič: Ostslavische Volkskunde. De Gruyter: Berlin,1927