On 14th January 1690 the clarinet was invented in Nürnberg, Germany by  the German instrument maker Johann Christoph Denner (or possibly his son Jacob Denner.

It had developed from much earlier reed instruments, going right back to Ancient Greece and Egypt. The chalumeau was a Baroque single reed woodwind instrument originating in France where its use spread to Germany.

Denner developed the instrument. He equipped a chalumeau in the alto register with two keys, one of which enabled access to a higher register. This second register did not begin an octave above the first, as with other woodwind instruments, but started an octave and a perfect fifth higher than the first. A second key, at the top, extended the range of the first register to A₄ and, together with the register key, to B♭₄. Later, Denner lengthened the bell and provided it with a third key to extend the pitch range down to E₃. – Wikipedia

Other makers added and developed the instrument further.