King Jangsu was the 19th ruler of the ancient Korean kingdom of Goguryeo, reigning from 413 to 491 AD. He is known for expanding the kingdom's territory and strengthening its military power. Under his leadership, Goguryeo became one of the most powerful states in East Asia. Jangsu's reign is also marked by significant cultural and economic development. He promoted trade and established diplomatic relations with neighboring states, including China and Silla. His efforts contributed to the prosperity and stability of Goguryeo during a crucial period in Korean history.