The nineteenth century was a period of important changes in literary, i.e. written, Finnish. These changes gathered pace after Finland became an autonomous Grand Duchy of the Russian Empire in 1809. The literature published prior to 1809, when Finland was still under Swedish rule, is considered separately in the section on Old Literary Finnish. From the 1810s onwards, the literary form of Finnish began to change gradually, although it was not until the early 1820s that the influence of Eastern Finnish dialects began to be felt more assertively in literary Finnish, which had hitherto been almost exclusively based on western Finnish dialects.
The ongoing battle between these two groups of dialects over their status in the evolving form of literary Finnish was still apparent in the language of the 1830s and 1840s, though literary Finnish subsequently took on a more stable form following the compromises achieved. The old foundation based on western dialects was retained in slightly revised form, and certain eastern dialect features were accepted into the written language. The new orthography finally became fully established when it was used in the Finnish translation of the Bible in the early 1850s.
In the decades that followed, there was a considerable expansion of the vocabulary and also revisions to the syntax of literary Finnish. Most of the phonological and morphological features that were still subject to variations in their use had started to take on their modern form by the start of the 1870s. Indeed, the period of Modern Finnish is considered to have begun by the time 1880 had been reached.