Bayan

Name of ancient Russian narrators and name of this instrument which is a modified accordion.

Some information from Wikipedia:

The bayan is a type of chromatic button accordion developed in Russia in the early 20th century and named after 11th-century bard Boyan.

The bayan differs from western chromatic button accordions in some details of construction:

* Reeds are broader and rectangular (rather than trapezoidal).
* Reeds are often attached in large groups to a common plate (rather than in pairs); the plates are screwed to the reed block (rather than attached with wax).
* The melody-side keyboard is attached near the middle of the body (rather than at the rear).
* Reeds are generally not tuned with tremolo.
* Register switches may be operated with the chin on some larger models.
* The diminished seventh chord row is shifted, so that the diminished seventh G chord is where one would expect the diminished seventh C chord in the Stradella bass system.
* Converter switches that go from standard preset chords to free bass (individual bass notes) are common on the larger instruments.
* Newer instruments may feature a register, where every tone played actually produces a perfect fifth.