Diocese of Finland was the predecessor of the Catholic diocese of
Turku. It was probably founded in the 12th century, but the
Bishop of Finland is first mentioned only in 1209. Diocese seems to have been independent on secular powers until the so-called
Second Swedish Crusade in 1249. The diocese was renamed as the
Diocese of Turku latest in 1259 by when it had been assimilated to the Swedish set of dioceses.