Prior to 600 AD, the lake M�laren was connected to the sea. Due to land elevation, the lake was slowly cut off, and boats had to be carried over land to and from the lake.
The name Telje is mentioned in the 11th century. To resolve a name conflict with another town that was founded north of Stockholm in the 17th century, S�der (meaning south) was added to create S�dert�lje; Norr (North) was added to the other to create Norrt�lje.
In the 18th century S�dert�lje had a charter. Due to the Great Northern War and a series of plague epidemics, the population of the city dipped to barely above 200
