Complex sentence: Cooperation ended in 1933, as Hitler came to power and created Nazi Germany, but some diplomatic initiatives continued through the 1930s, culminating with the Molotov-Ribbentrop Pact of 1939 and various trade agreements.
Split into simpler sentences: Cooperation ended in 1933, as Hitler came to power and created Nazi Germany. The countries' economic relationship dwindled at the begining of the Nazi era, but some diplomatic initiatives continued through the 1930s, culminating with the Molotov-Ribbentrop Pact of 1939 and various trade agreements.