When did the Nazis begin deporting jews to poland

Nazis started deporting Jews to Poland in 1942. They didn't deport Jews just from the countries which were occupied by The German Reich, but even from countries which were German allies. Jews were deported from The Netherlands, Belgium, France, Italy, The German Reich, Slovakia, Romania, Bulgaria, Serbia, Hungary, Croatia and Greece. From 1942. until the very end of the war, trains transported people to great extermination camps in Poland, or even to overcrowded concentration camp in Germany.