Simplify the following text for a Grade 8 native English-speaking person.
Original: 1946 marked the beginning of the tenure of maestro Herbert von Karajan who , though not principal conductor , worked with the VSO in the `` Karajan Series '' concerts , going on extensive tours throughout Europe and North America .
Simplified: From 1946 they were often conducted by Herbert von Karajan who toured with them throughout Europe and North America .