It's name is 105/22 mod 1961 and it has a very long and interesting story.

During the WW I the austro-hungarians used a 10 cm M14 howitzer. After the war the italians captured many of them and used as 100/17 mod 1914 up to the WW II and even later.

Immediately after WW I, Skoda kept producing artillery pieces and evolved the design into a 100/22, the vz19 you can see in Brussels. At that time the austro-hungarian empire was already gone, so it was a czechoslovakian gun.

The gun was acquired, among others, by Poland and Yugoslavia.

In 1941 the italians captured a bunch of these from the yugoslavian army, and immediately put them into service, since they shared the same ammo with the 100/17. Italians also obtained more guns from the germans (captured from Czechoslovakia, Poland and Yugoslavia).

The most amazing thing is that after WW II the italian army updated these guns. They were rechambered to 105 mm (to use standard NATO ammo), got a muzzle brake, a Hogg Device (from 25 pdr) and entered service as 105/22 mod 1961.