The castanets belong to the idiophones, the self-toners or self-sounders. The instrument itself vibrates and does not need strings or a membrane to produce sounds. In the group of idiophones, castanets belong to the counter-strike instruments and can be found all over the world.

Probably the preforms of the castanets are the oldest instruments of mankind. Two sticks, stones, conch shells were used to beat rhythms, mostly in ritual dances. They were played in all cultures and on all continents.

In Greece they were called
Krótalos (Greek crotos – pulse).
In Roman times and in Hispania (Latin name for the Iberian Peninsula).
Crusmata (Latin crusma: a music accompanying played on a percussion instrument).
In Spain
Castañeta, Castañuela or Palillo (little stick).

By the way: the rhythm with 2 spoons in Bavarian folklore is also an idiophone. And this practice of playing with spoons is also widespread all over the world.

According to a Japanese legend, when music was invented, the gods themselves stroke the beat on them, on ‘the mother of all instruments’.