Episode 3: The King Gwanggaeto Stele: The Key to Goguryeo's Secrets. The stele erected in honor of King Gwanggaeto the Great is the oldest extant record on Korean history. In contrast to the 12th-century text History of the Three Kingdoms, which was a chronicle of an even earlier era, the stele contains the annals of the king's reign as recorded by his own retainers. The stele is the sole remaining eyewitness to the achievements of King Gwanggaeto. Episode 4: Tomb Murals: Bringing Goguryeo Back to Life. 1500 years ago, Goguryeo was the dominant power in Northeast Asia, but no written records from that period have survived. We do not know how the people of Goguryeo lived, what they ate, where they lived, and what they wore. However, information on their lives can be found in the tombs of Goguryoe people. The source for this information is the wall paintings in those tombs.