Japan was suffering in the Great Depression
Much of its economy was based on exporting silk to rich countries like the USA
However, silk is a luxury item, and people cut back on luxuries when their families were starving
So Japanese industry was in decline and many people were unemployed
By 1932 silk was worth one fifth of what it had been sold for in the early 1920s and production and employment had fallen by 30 percent by 1931
Japan is made up of small islands, with very little open space and few natural resources
Therefore, when the Great Depression hit, Japan had to start looking elsewhere for its resources
Manchuria, with its fertile farmland, industry and natural resources, seemed like a good place to invade