Why did North Korea and South Korea divide into two different countries?
It all started after WWII when Russia and the US chose what to do with Korea. They divided it by the 38th parallel, North going to Soviet Russia (communist) and South going to the US (democracy). This led to the division of the country and government.
The countries did start out as one. The division of Korea occured when the aftermath of Worls War II left the northern part of Korea under Soviet occupation and the south under the occupation of the other allied countries. This separated Korea, making two different countries. Soon Soviet-ruled North Korea invaded South Korea, resulting in the Korean War. Many were killed, and the countries have remained divided ever since.
The Democratic People's Republic of Korea (North) and The Republic of Korea (South) are two different countries divided after WWII defeat of Japan who occupied the Korean Peninsula. The USSR occupied the North and The USA occupied the South. They were never reunified despite Northern Efforts in The Korean War.