It was most likely made in the 1930s in Germany.
JGA was actually J. G Anshutz Germenwaffenwerk A G Zella-Mehlis/ Thur (Thurungia) - aka Anshtuz.
Karabiner = "carbine".
Prior to WWII, Germany was legally allowed to produce only .22's for civilians and they werent allowed to produce more than a certian amount of firearms for the military..
Many of the Karabiners were used as military trainers.
After WWII, during the US/Soviet Occupation of Germany, the destruction of all German guns was ordered - so many of the survivers were GI takeback/capture guns.