September 9, 1948 Haeju
Founding of the Democratic People's Republic of Korea

  Shortly after the founding of the ROK, North Korea founded the DPRK (Democratic People's Republic of Korea), headed by Kim Il-Sung.  They claimed  that their government was the only one established by legal measures, but the December UN Conference in Paris affirmed that ROK was the only legal government on the Korean peninsula.  

Economically, the North had a far better start than the South.  They were blessed with abundant natural resources and many industries.  They were more advanced in terms of national security as well, for the Soviet Union supplied them with weapons and other military equipment.  In addition, towards the end of 1949, Korean soldiers who had fought in China's Civil War came down to North Korea and joined their army, strengthening it even more.