The original language of Scandinavia was Proto Norse a common Germanic language that evolved into Old Norse during the 8th Century. Over time two distinct dialects arose, Old West Norse which was spoken in Norway and Iceland, and Old East Norse which was spoken in Denmark and Sweden. From around 1100 onwards a diversion occurred within Old East Norse regarding runic inscriptions, which led to Denmark and Sweden speaking different yet related languages.
Starting in around 1225 Old Swedish, as the language became to be known gained popularity in Sweden. It was influenced by the arrival of Christianity in Sweden and the exposure to Latin. Both Greek and Latin word began to see more usage and with the rise of the Hanseatic League during the 14th Century Dutch and German immigrants to Sweden brought their influences into the language. Gender systems, pronouns, adjectives and key numerals were all added during this period.
Modern Swedish is largely believed to have begun in 1526 with the introduction of the printing press, and the printing of the first New Testament in Sweden. This period of European Reformation was vital in the development of many modern European languages.
The blackletter or Gothic typeface used during this period made it unclear which nouns should be capitalized, but the introduction of the Latin typeface antiqua in the 18th Century led to the capitalization rules that we see today.