Gwanggaeto the Great was a king of the ancient Korean kingdom of Goguryeo, reigning from 391 to 413 AD. He is known for his military conquests and expansion of the kingdom, which at its height covered parts of modern-day Korea, China, and Russia. His reign marked a significant period of growth and power for Goguryeo. Gwanggaeto is also recognized for his contributions to Korean culture and history. He is often celebrated in Korean folklore and is featured in the Gwanggaeto Stele, a stone monument that commemorates his achievements and serves as an important historical source for understanding the era.