Why was Finnish literature limited before the Reformation?

Before the Reformation, written literature in Finland was extremely limited because the region lacked a standardized written tradition in the Finnish language. During this period, Finland was under Swedish rule, and Swedish served as the language of the upper classes, government, and education.123

While there was a rich tradition of oral poetry consisting of epic sequences and songs transmitted through generations, these were not formally recorded in writing until much later. The transition to a written literary culture began only with the work of the religious reformer Mikael Agricola, who established the foundation for literary Finnish in the 16th century by publishing a primer and translating the New Testament into Finnish. Prior to this, literary expression in Finland was largely confined to religious songs in Latin or works produced in Swedish.4152