The currency used from the 17th Century to 1873 was the Riksdaler. The system was quite complex, with subunits consisting of mark, öres, pennings, skillingars, and runstyckens. In 1855, Sweden adopted the decimal system when they introduced a new version of the Riksdaler: the Risksdaler Riksmynt. The Swedish Krona first came to existence when Sweden agreed to join the Scandinavian Monetary Union in 1873, alongside Denmark and Norway. All countries involved fixed their respective currencies against gold at par with one another to create monetary stability. This union lasted until World War I, when the countries lost their pegs to gold. Sweden kept the Krona currency after the monetary union was disbanded.