Folk Suvaro-Bulgar-Chuvash instruments were classified by sound source into: hĕlĕkhlisem (string), vĕrmellisem (wind), çurhalisem (membrane), and hăy tĕllĕn yanrakannisĕm (self-sounding).

In hĕlĕkhlĕ (string) instruments, sound was produced by one or several strings stretched between fixed points over a resonator. The strings were set in motion either by a bow or by fingers, and accordingly these instruments were divided into sĕrkĕchlisem (bowed) and turtăçlisem (plucked).

The sĕrkĕchlĕ (bowed) category included two types of sĕrme kupăs (violins) with carved and composite bodies. Sound on these instruments was produced using a sĕrkĕch (bow).

Variants of the name included kupăs, sĕrme kupăs, and hăma kupăs. According to an unknown 19th-century author, no household celebration, wedding, funeral, or memorial gathering took place without violin playing.

In legends and tales, the violin was attributed divine origin. The kupăs (violin) accompanied a person throughout life — from birth to the very end of the life journey. Its popularity is reflected in the fact that the term kupăs was also used to name other instruments: tuta kupăs (accordion), timĕr kupăs, văruan (jaw harp), and others.

Research into the Chuvash language and musical artifacts indicates that such instruments existed among the Suvaro-Bulgars during the period when their distant ancestors — the Subarians — lived in Western and Central Asia, the Caucasus, and the Black Sea region long before the Common Era.

The Bulgarian historian S.G. Donchev reports that the string instrument (both bowed and plucked) was known to many Mediterranean peoples under names derived from the ethnonym Bulgar: in Turkey, France, and Algeria as bulgarina, in Spain as bulgarija, and in Serbia, Croatia, and Albania as bulgary.