The written sources for the history of medieval Finland—traditionally dated from the first Swedish crusades around 1150 to the end of the Kalmar Union and the beginning of the Reformation around 1520—have a character all their own. Unlike many regions that preserved long and centralized state archives, medieval Finnish materials are not so much scarce as they are fragmented, scattered, and often found in unexpected forms.
During this period, the territory of present-day Finland was not an independent state but formed the eastern part of the Kingdom of Sweden. The main administrative, religious, and literate authority in the region was the Catholic Diocese of Turku (Åbo). As a result, the surviving written records do not represent a Finnish state archive but rather the documentation of a Swedish diocese, supplemented by material from Swedish castles, foreign merchants, and various external political and ecclesiastical powers.
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The Great Fragmentation and the "Fragmenta Membranea"The Great Fragmentation and the "Fragmenta Membranea"
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A common misconception is that Finland lacks a medieval archive. In fact, it once had one—but it underwent a unique process of dismemberment and reuse that paradoxically ensured its survival in fragmentary form.
This fragmentation was largely caused by the Lutheran Reformation under King Gustav Vasa in the 1500s. When the Catholic liturgical books—missals, breviaries, and antiphonaries—became obsolete, they were not simply destroyed. Instead, their durable parchment leaves were reused as covers and bindings for new tax records known as the Voudintilit (Bailiffs’ Accounts). These tax accounts, compiled throughout the Swedish realm, were later stored in Stockholm. After Finland was annexed by Russia in 1809, the archival materials concerning Finland, including these accounts and their medieval parchment covers, were moved to Helsinki. This transfer separated many fragments of the same original manuscripts between the archives of Sweden and Finland.
The recycled fragments now form the Fragmenta Membranea collection at the National Library of Finland. It contains over 9,000 parchment leaves from roughly 1,500 to 1,700 different manuscripts—by far the largest surviving body of medieval literature from Finland, where only a few dozen complete codices remain. Most of the material is liturgical, though some fragments include legal, philosophical, and other texts.
The "Registrum Ecclesiae Aboensis" (Black Book of Turku)The "Registrum Ecclesiae Aboensis" (Black Book of Turku)
While fragments make up most of the surviving literature, the central monument of Finland’s medieval written heritage is the Registrum Ecclesiae Aboensis (REA), often called the Black Book of Turku Cathedral.[1] This cartulary, compiled by the Chapter of the Diocese of Turku in the late 1400s, contains copies of hundreds of documents dating from the early 13th to the early 16th century.
The REA was created for practical, not historical, purposes—it was meant to preserve legal and administrative records. It includes charters concerning church properties, fisheries, privileges, land sales, indulgences, and inventories of altars and relics. The book survived the Reformation intact because its contents, dealing with property and rights, were of direct interest to the Crown during the confiscation of church lands.
Administrative and Legal SourcesAdministrative and Legal Sources
The Voudintilit (Bailiffs’ accounts)The Voudintilit (Bailiffs’ accounts)
The Voudintilit serve a dual role in Finnish historical research. As early modern administrative records, covering the years 1537 to 1634, they provide the first comprehensive overview of Finland’s population and economy, listing taxes, landholdings, deserted farms, and tithes. At the same time, the volumes themselves are invaluable because they physically preserve the medieval Fragmenta Membranea as their bindings.
External sourcesExternal sources
Because Finland’s own medieval archive is incomplete, many crucial records are preserved abroad.
- Hanseatic Archives: German merchants of the Hanseatic League dominated Finland’s medieval trade, especially in Turku and Viipuri (Vyborg). The main sources for this economic activity are found in Hanseatic city archives, particularly in Lübeck and Tallinn. Merchant letters and account books reveal extensive trade networks that included Finnish ports.
- Russian Chronicles: The earliest written accounts of conflicts in the region, from the 11th to the 14th centuries, are found in Russian chronicles such as the Novgorod First Chronicle. These texts record raids and military campaigns against the peoples of southern and central Finland.
- Vatican Archives: As part of the Catholic Church, the Diocese of Turku also appears in papal records. Letters, petitions, and administrative documents concerning Finnish bishops, church disputes, and indulgences are preserved in the Vatican’s archives.
Material and Linguistic SourcesMaterial and Linguistic Sources
In addition to written records, Finland’s medieval past is also documented through physical and linguistic evidence.
- Archaeology – Churches and Castles: The 104 medieval stone churches—83 of which still stand—together with major castles such as Turku, Hämeenlinna, Viipuri, and Olavinlinna, form some of the most tangible records of the era. Their architecture and locations reflect the spread of Christianity and the consolidation of Swedish rule.
- Onomastics – Place and Personal Names: The study of medieval place and personal names offers insight into settlement history, land use, and the transition from pagan to Christian culture. Many of these names were first recorded in the 16th-century Voudintilit.
The Diplomatarium Fennicum DatabaseThe Diplomatarium Fennicum Database
Today, digital technology helps to reunite Finland’s dispersed medieval archive. The Diplomatarium Fennicum (df.narc.fi), maintained by the National Archives of Finland, compiles all known documents concerning medieval Finland and its inhabitants. It builds upon the earlier printed series Finlands Medeltidsurkunder and includes the complete texts of the Registrum Ecclesiae Aboensis, medieval charters, gravestone inscriptions, and fragments of chronicles.
Through this digital platform, Finland’s fragmented medieval record is once again brought together—virtually restoring the archive that history once scattered.
See alsoSee also
Explore more about Genealogy Sources In Medieval FinlandExplore more about Genealogy Sources In Medieval Finland
- Finland - Collection Catalog at MyHeritage
- Finnish Medieval (1100-1525) Genealogy project at Geni
- Research Finns – Finnish not required; Internet is! webinar at Legacy Family Tree Webinars
References
- ↑ Reima Välimäki & Kirsi Salonen (2022). The Materiality of Turku Cathedral’s Spiritual Treasury: Indulgences. Material Religion.