How North Korea came to be
North Korea began with the seperation of the Korean peninsula at the end of WWII in 1945. Japan reigned over the Korean Peninsula in WWII. After Japan was defeated the Korean Peninsula was divided at the 38th parallel. The United States took control of the Southern division and the Soviet Union took the North division. This was meant to be temporary and was supposed to return to a single Korean nation, after the United States, Soviet Union and other countries could construct a government.
Unfortunately The United States and Soviet Union weren't able to agree on the initiation of a Joint Trusteeship over Korea. Therefore the two nations of North and South Korea emerged in 1948. The communist North Korea or Democratic People's Republic of Korea DPRK claimed to hold legitimate power over all Korea. At the same time The First Republic of Korea or South Korea claimed the same. These claims led to the Forgotten War or Korean War in 1950. Many claim that this was also the start of the Cold War and for the United States a war against communism altogether. The war ended in July 1953. The war had an estimated death toll of 5 million soldiers and civilians . In the end neither country reigned over the peninsula and ever since has been divided into two nations. The peninsula is divided by the Korean Demilitarized zone.
The two sides still continue with tensions. Kim Il-Sung died in 1994. He developed a principal of Juche meaning self-reliance but due to the collapse of the Soviet Union, major floods and droughts throughout the region the rogue nation enter an economic crisis in the years before Kim Il-Sung passed away.
Kim Jong-Il succeeded his father in 1994 and ruled North Korea with a military fist. The nation suffered from famine and poor human rights partly due to the management by Kim Jong Il. In 2011 the government announced that Kim Jong Il had died and Kim Jong Un had taken power. In the years since, he has worked vigorously on the country's nuclear and missile program causing international alarm and forcing the UN place sanctions on Kim Jong Un and his country.
sources: https://en.m.wikipedia.org/wiki/History_of_North_Korea