Complex sentence: He was the youngest son of Magnus Eriksson of Sweden and Blanche of Namur, his older brother, Eric Magnusson was King of Sweden until he died and Haakon succeeded him, although his rule over Sweden was brief.
Split into simpler sentences: He was the youngest son of Magnus Eriksson of Sweden and Blanche of Namur. His older brother, Eric Magnusson was King of Sweden until he died and Haakon succeeded him, although his rule over Sweden was brief.