This period was known as the baby boom, and this generation is still referred to as the "baby boomers," this being because there was a huge increase in the birth rate as people returned home from the war.
Shang rulers expanded their kingdom by land purchases which expanded their borders.
Hope this helps:)
The radiation left after the war. Along with the many people who died thereafter for many years. This also caused a nuclear war of sorts later on with Russia.