Obviously Korea was one before 1945. But what was the northern part of Korea like before 1945? The USA is a big part of the blame for the split and I am assuming after 1945, the quality of life declined a great deal.
All of Korea was occupied for years by the Japanese during WWII. They put much of the population into forced labor or to be prostitutes for the Japanese army, or worse. So if you want to know what it was like in NK before 1945, you can bet it was MUCH worse than it is now.
The Northern half of the Korean Peninsula was significantly more industrialized than the South, which was almost entirely agrarian.