Few parts of Europe changed borders as often as the Czech and Slovak lands, and the changes shape your family research. The village your ancestor left may have been in the Austrian Empire or the Kingdom of Hungary, then in Czechoslovakia, then in Nazi-occupied territory, and today in the Czech Republic, Slovakia or Ukraine. Its records, its language and even its name depend on which period you are looking at. This guide explains the timeline, the regions, the communities and what each means for records. We checked these details in October 2026, and archive holdings, statistics and online collections change, so confirm them before you rely on them.
A timeline of the borders
| Date | What happened | Why it matters for records |
|---|---|---|
| Until 1918 | Bohemia, Moravia and Austrian Silesia were Habsburg lands, and the territory of present-day Slovakia belonged to the Kingdom of Hungary | Registers in Latin, German or Hungarian, and Hungarian place names in Slovakia |
| 28 October 1918 | Czechoslovakia was proclaimed in Prague, and the Slovaks officially joined two days later | Slovak and Czech names came into official use after 1918 |
| 30 September 1938 | The Munich Agreement forced Czechoslovakia to cede the Sudetenland to Germany. Bohemia and Moravia lost about 38 percent of their combined area, with some 3.2 million Germans and 750,000 Czechs | German-speaking border regions became part of Germany |
| Autumn 1938 | Southern Slovakia and Subcarpathian Ruthenia went to Hungary under the First Vienna Award of 2 November, and the Zaolzie region in Silesia went to Poland | Records of southern Slovakia and Ruthenia reflect Hungarian administration until 1945 |
| March 1939 | Germany occupied the rest of Bohemia and Moravia as a protectorate, and the Slovak State was declared on 14 March 1939 | Two separate administrations until 1945 |
| 1945 | Czechoslovakia was re-established, except for Subcarpathian Ruthenia, which was ceded to the Soviet Union in June 1945 | Ruthenian records are now in Ukraine |
| 1 January 1993 | Czechoslovakia split peacefully into the Czech Republic and Slovakia | Two states, two sets of archives and two citizenship laws |
The regions
- Bohemia and Moravia. The core of the Czech lands, with the best-digitized registers. See our Czech parish registers guide.
- Czech Silesia. The northeast of the Czech Republic, whose archive is the Opava Land Archive. Zaolzie was ceded to Poland in 1938.
- Slovakia, or Upper Hungary. Records and place names reflect the Kingdom of Hungary. See our Slovakia guide.
- Subcarpathian Ruthenia. Now in Ukraine, the western homeland of many Rusyns. See our Carpatho-Rusyn guide.
Communities with their own records and languages
- Sudeten and German-speaking Bohemians. More than three million Germans lived in Prague and the border regions of Bohemia, Moravia and Silesia, about 23 percent of Czechoslovakia’s inhabitants, and the expulsion of 1945 and 1946 moved most of them to Germany and Austria. See our guide.
- Carpatho-Rusyns. Eastern Slovakia has Greek Catholic parishes, Cyrillic signs and dual place names.
- Hungarian-speaking Slovaks. In the 2021 census, 456,154 people in Slovakia, 8.37 percent, declared themselves Hungarian, and they form the majority in the districts of Komárno and Dunajská Streda. See our guide.
- Jewish families. The Jewish community registers for the Czech lands are held by the National Archives, and JewishGen covers Slovak civil records. We point to these specialist resources without covering them in depth.
What this means for your research
- Date your ancestor’s life against the borders. A birth in 1880 and a birth in 1925 in the same village may have been in different states.
- Choose the archive by present-day location, not by the state your ancestor remembered. The Czech regional archives and Slovak state archives hold the registers. See the records hub.
- Expect several language forms of the village name. See how to find the village of origin.
- Expect different languages in the registers for the same family across periods. See our guide to reading the records.
- Check the censuses. Declarations of ethnicity changed with borders: in Košice, 75.43 percent declared Hungarian nationality in 1910, and only 21.2 percent did in 1920, according to a study of the city. See our guide to censuses.
Borders and citizenship
The same history appears in citizenship law. A summary of the Czech Citizenship Act says the declaration route does not apply to people who lost Czechoslovak citizenship under the postwar presidential decree on persons of German and Hungarian nationality, or under the treaty on Subcarpathian Ruthenia. In August 1945 a constitutional decree denied Czechoslovak citizenship to persons of German and Hungarian ethnicity who had become German or Hungarian citizens during the war, according to Radio Free Europe. See the citizenship guide.
Emigration from the regions
Where your family came from affected where it went. Czechs went mainly to the Midwest and Texas, Slovaks and Rusyns mostly to Pennsylvania, including its coal region and the Pittsburgh area, and German Bohemians are usually counted as German Americans. See our guide to emigration to America.
A regional research routine
- Place the village on a modern map and an old map, and note the present-day country.
- List the periods your ancestors lived there and the state that governed each.
- Identify the language and church of the family.
- Choose the archive and register type accordingly.
- Search under every name form.
- Compare the censuses with the registers, and note any declared ethnicity or language.
Illustrative composite (not a real family): A reader’s family came from a village in southern Slovakia. Her great-grandfather was born in 1884 under the Kingdom of Hungary, her grandfather in 1921 in Czechoslovakia, and her father in 1942 in a village that was again part of Hungary, where the registers may differ in language. She searches the Latin and Hungarian registers of the parish, and learns to expect Hungarian names for the village in the earlier records.
Which archive for which region
| Area | Where the registers are |
|---|---|
| Prague | Prague City Archives |
| Central Bohemia | SOA Praha, with its eBadatelna portal |
| Western Bohemia | The regional archive, via the Porta fontium portal |
| Southern Bohemia | The Třeboň regional archive, via České archivy |
| Northern Bohemia | The Litoměřice regional archive |
| Southern Moravia | The Moravian Land Archive in Brno, via Acta Publica |
| Northern Moravia and Silesia | The Opava Land Archive |
| Slovakia | The Slovak state archives, with FamilySearch’s digitized books |
| Subcarpathian Ruthenia | Archives in Ukraine, with some Greek Catholic records on FamilySearch |
Match an old map to a new one
Find your village on a modern map and then on a map from the period you are researching. Wikipedia’s village pages for Slovakia give Slovak, Hungarian and, in the east, Rusyn names, and note the Hungarian county before 1918, which helps you identify the right place. Write down the county or district, because many villages share a name. See our village-of-origin guide.
Families that crossed borders
The Austria-Czech special interest group at JewishGen groups Bohemia, Moravia, Silesia, Slovakia and Subcarpathian Ruthenia together because these groups lived together for more than a generation and intermarried. A family may therefore have a Czech branch, a Slovak branch, a German-speaking branch and a Hungarian-speaking branch, with different archives, languages and name forms. Treat each branch with its own method.
Questions to ask for each ancestor
- Where was he born, and which state governed that place then?
- What language did the family speak, and what church did it belong to?
- Which archive holds the registers for that parish today?
- What name forms did the village have in the Czech, Slovak, German and Hungarian languages?
- Did the family move across a border, or did the border move across the family?
Common mistakes
- Assuming one country throughout. The state changed several times.
- Searching only today’s name. Older records use other forms.
- Ignoring the minority communities. Their records and languages differ.
- Overlooking Ruthenia. Its records are in Ukraine.
- Taking a declared ethnicity as fixed. It changed with borders.
Browse every guide in Regions, Borders & Emigration. Sources include Wikipedia on Czechoslovakia, Wikipedia on the Second Czechoslovak Republic, a Slovak law firm’s summary of Czech citizenship by descent, Radio Free Europe on the Beneš decrees and the Slovak Nation’s Memory Institute on the First Vienna Award.
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