The Swedish province of Uppland has been a stronghold for nyckelharpa music since the early 17th century, including musicians like Byss-Calle (Carl Ersson Bössa, 1783–1847) from Älvkarleby.
Eric Sahlström (1912-1986 CE) was a Swedish player of the nyckelharpa, and riksspelman awardee from Tobo in northern Uppland, Sweden.
Carla Kihlstedt: violin, Percussion-guitar, bass harmonica, nyckelharpa
He is the initiator and conductor of the "European Nyckelharpa Training", that takes place in co-operation of the "Scuola di Musica Popolare di Forlimpopoli", Italy, the academy "Burg Fürsteneck" near Fulda, Germany, and the "Eric Sahlström Institutet" in Tobo, Sweden, as a vocational trainer for musicians on the Nyckelharpa.
A Swedish scholar, Per-Ulf Allmo, has suggested that the instrument and another in the same style were probably built in Särna, northern Dalarna around 1680, with Praetorius as inspiration, and with no close affinity with the nyckelharpa tradition in northern Uppland, the stronghold of the instrument.
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The soundbox has an hourglass shape and looks very much like the illustration of a nyckelharpa in Michael Praetorius's Syntagma Musicum III of 1620 (where it is called Schlüssel fiddel).