As a part of the effort to establish an accurate identity of Korean culture, a new stamp was issued by Korean Post. It is dedicated to Daejoyeong of the Balhae Kingdom.
In the aftermath of the downfall of Goguryeo in 668, the Tang Dynasty forced many drifting Goguryeo people to move to Tang. At the time, Daejoyeong was also taken to Tang together with the multitude of those drifting people. When the Kitan tribe rose in revolt, Daejoyeong, who had been subjugated by Tang, mustered the drifting Goguryeo people to stand up to Tang. At Cheonmunryeong, Daejoyeong soundly defeated the Tang army after it had been chased across the Lia-Ho River. He rallied the drifting Goguryeo and Malgal people and built a castle on Dongmo Mountain to establish the Balhae Kingdom in 698. Thanks to its insurmountable bravery, Balhae established a grand empire encompassing what is now Manchuria of China, the Yunhaju of Russia, and most of the North Korean territory, securing the largest area in Korea's history. Balhae, which succeeded Goguryeo, based its tradition and culture on Goguryeo, accepted the Tang civilization and established a splendid history and culture, thus being called "Haedongseongguk" which means "a thriving country to the east of the sea." Since its foundation in 698, Balhae shared a border with Silla with Balhae in the north and Silla in the south for about 230 years, only to collapse in 926 due to the invasion of the Kitan tribe.