In the Middle Ages, there were many Slavic tribes across a wide stretch of land. A large portion have long since been consigned to the history books, but a fair number live on in their descendants.
From these disparate tribes came modern-day Russians, Poles, Ukrainians, Belarusians, Bulgarians, Moldovans, Czechs, Slovaks, Serbs, Sorbians (mostly found in Germany today), Goryuns (a minority group in Ukraine), Silesian Germans, Kashubians (an ethnic group in Poland), Moravians, and Croatians.
Some of the extinct tribes also lived on lands which are today part of Montenegro, Macedonia, Slovenia, Austria, Greece, Hungary, and Bosnia.
Until about 500 CE, there was a Proto–Slavic language, descended from Proto–Balto–Slavic and ultimately Proto–Indo–European. Then, by the 7th century, it splintered into many dialects. When Orthodox Christians were compelled to use Church Slavonic, much vernacular was lost.
The Slavic language family eventually broke into East, West, and South branches. Some linguistics believe there also once existed a North branch.
If you can read any of the modern Cyrillic alphabets, you can decipher a good portion of the Early Cyrillic alphabet, which is still used to write Church Slavonic. The trickiest thing is how the letters are formed. It’s more like artsy calligraphy than plain block printing.
It’s quite a bit harder to decipher Glagolitic script, the oldest known Cyrillic alphabet. It was created by Sts. Cyril and Methodius in the 9th century. There are almost no letters in that alphabet I can recognize.
History of naming patterns:
In the pre-Christian era, children under the age of 7–10 had “substitutional names” meant to trick evil spirits. This was a result of high childhood mortality. Kids who managed to survive at least to age 7–10 were considered special, worthy of a real name and adult status. This new adult name was bestowed during a ritual haircut.
Non-Christian names were banned by the Council of Trent, but Polish nobility (esp. Protestants) tried to preserve their real names. Commoners mostly chose names from the Church calendar, on which only a handful of Slavic names were represented.
Exceptions were made for names whose meanings referenced God, such as Bogdana, Boguslav, and Bogumila.
Many Old Slavic names contain the elements mir(a) (world; peace), mil(a) (precious), and slav(a) (glory). Names ending in these elements are used by both sexes (with the feminine forms ending in -a). After Christianization, many of these names were replaced by Slavified versions of Greek saints’ names.
Names derived from simple nouns and adjectives were typically used by peasants. Such names include Vesna (Spring), Zora (dawn), Brana (to protect), Plamen (flame), Vuk (wolf), and Mladen (young).
Other single-source names expressed affection, hope, and good wishes for newborns.
Names with two root words were also popular, intended as wishes for newborns. Examples include Zbigniew (to expel anger), Kvetoslava (flower of glory), Rodimir (family peace), and Vratislava (to bring back glory).
Agneszka, Aneszka (Agnes)
Bogdana (Given by God)
Desislava (Tenfold glory)
Dragoslava (Precious glory)
Lyudmila (Favour of the people)
Miloslava (Gracious glory)
Radoslava (Happy glory)
Regelinda (Soft advice)
Rogneda, Ragnedda (Battle advice)
Slavitsa (Little glory)
Stanislava (To become glory)
Tomislava (Torture glory)
Yaroslava (Fierce glory)
Berislav (To gather glory)
Blazh (Sweet, blessed, pleasant)
Bogdan (Given by God)
Bogumil (Favoured by God)
Bogumir (Great God or God’s peace/world)
Boguslav (Glory of God)
Boleslav (Greater glory)
Borislav (Battle glory)
Borisu (Snow leopard, wolf, or short)
Borivoy (Battle soldier)
Bozhidar (Bozho) (Divine gift)
Bratomil (Gracious brother)
Bratoslav (Brotherly glory)
Bronislav (Protection and glory)
Chedomir (Child of peace/the world)
Chestibor (Battle of honour)
Chestirad (Happy honour)
Chestislav (Honour and glory)
Dalibor (To fight from a distance)
Desislav (Tenfold glory)
Dobrogost (Good guest)
Dobromil (Good and gracious)
Dobroslav (Good glory)
Dragomir (Drashka) (Precious glory) (love this name!)
Gostislav (Glorious guest)
Kazimir (To destroy peace/the world)
Krasimir (Beauty of the world/peace)
Kresimir (Spark of peace; to rouse the world)
Lyubomir (Love of the world/peace)
Lyudmil (Favour of the people)
Mechislav (Sword of glory)
Milivoj (Milosh) (Gracious soldier)
Milodrag (Milosh) (Dear and precious)
Milogost (Milosh) (Gracious guest)
Miloslav (Milosh) (Gracious glory)
Miroslav (Peace/The world and glory)
Mislav (Thought of glory; my glory)
Mstislav (Vengeance and glory)
Ninoslav (Glory now)
Premislav (Glory stratagem)
Premysl (Stratagem, trick)
Pridbor (First battle)
Radomil (Happy and gracious)
Radomir (Happy peace/world)
Radoslav (Happy glory)
Radovan (One who brings joy)
Ratimir (Battle of peace/the world)
Rostislav (Growth of glory)
Slavomir (Glory of the world/peace)
Sobeslav (Glory for oneself)
Stanimir (To become peace)
Stanislav (To become glory)
Svetopolk (Blessèd people)
Svetoslav (Blessèd glory)
Tikhomir (Quiet peace/world)
Tomislav (Torture glory)
Veceslav, Vecheslav (More glory)
Velibor (Great battle)
Velimir (Great peace)
Vitomir (Master of peace/the world)
Vladimeru, Vladimir, Volodimeru (Vova, Volodya) (Famous rule)
Vladislav, Volodislavu (To rule in glory)
Vlastimir (Sovereignty of the world/peace)
Vlastislav (Sovereignty of glory)
Voitsekh (Soldier of comfort/solace/joy)
Vratislav (To return in glory)
Vsevolod (Seva) (To rule all)
Yarognev (Fierce anger)
Yaromil (Fierce and gracious)
Yaromir (Fierce peace)
Yaropolk (Fierce people)
Yaroslav (Fierce glory)
Zbignev (To dispel anger)
Zdislav (To build glory)
Zhelimir (To wish for peace)
Zvonimir (The sound of peace)