Which Finnish epic influenced J.R.R. Tolkien’s development of Middle-earth?

The Finnish epic The Kalevala influenced J.R.R. Tolkien’s development of Middle-earth.

Tolkien encountered Finnish while studying languages and was particularly impressed by the structure and sound of the language. The Kalevala, compiled by Elias Lönnrot from Finnish and Karelian oral poetry, supplied ideas that contributed to Tolkien’s early mythology and to the story of Túrin Turambar. Its tragic heroes, songs, transformations, and ancient atmosphere resonated with Tolkien’s interest in creating a connected body of legend.

The Kalevala was not a direct blueprint for The Lord of the Rings. Tolkien drew on many traditions, including Germanic, Norse, Finnish, and medieval English sources, while combining them into his own mythology. The Finnish influence is also visible in the development of Quenya, one of his Elvish languages, whose sound and structure were partly inspired by Finnish.