Southern Sweden is considered, even by many Swedes, to be a world of its own. Once a part of Denmark, the region is clearly distinguished from the rest of the country by its geography, culture, and history. Småland, the northernmost of Sweden's southern provinces, is also the largest, but its harsh countryside and poorer, bleaker way of life led thousands to emigrate to the United States in the 19th and 20th centuries.
Those who stayed behind developed a reputation for inventiveness. The area has many small glassblowing firms, and it is these glassworks, such as the world-renowned Kosta Boda and Orrefors, that have given the area the nickname the Kingdom of Glass. Kalmar was a rather important outpost from the 13th to the 17th centuries because it was one of the southernmost cities in Sweden. However, in the Treaty of Roskilde, the King of Denmark–Norway was forced to cede what is now southern Sweden, and the town's importance diminished gradually over the years as its fortress no longer defended the country's southern border. Now the Öland Bridge makes it the gateway to that island.