The Joseon Dynasty
In 1392 A.D., a dynasty known as the Joseon Dynasty came to power in Korea. Joseon rulers built a new capital city, which they named Hanyang. Hanyang would become the present day city of Seoul, which for many years was the modern capital of Korea.
Under Joseon rulers, the Koreans developed many cultural advancements, including an alphabet, advancements in weather forecasting, and advancements in war technology.
These advancements in wartime technologies helped them to defend themselves against outside attacks, and allowed them to maintain their independence for centuries.