The most popular traditional stringed instruments in Estonia are various types of kannel (zither), bowed harp, fiddle, and psalmodikon. Kannel comes in four types and is the oldest known instrument in Estonia, dating back around 2,000 years. The bowed harp reached Estonia through Swedish settlers and is played by placing it on the knees and bowing 3-4 horsehair or sheep intestine strings. Fiddle came to Estonian towns in the 17th century and spread among peasants in the 18th century, eventually replacing bagpipes. Psalmodikon is a relatively new instrument dating from 1829 based on a monochord with a single bowed string.