These two volumes are from Yongbi Ŏch’on’ga (Songs of the Dragons Flying to Heaven), volumes 9 and 10 (of 10), printed in the late fifteenth century from the original blocks. Songs of the Dragons Flying to Heaven is a poem in 125 cantos, written in Korean, with a Chinese translation following. It was commissioned by King Sejong (1419-1450) and was compiled in 1445 by three court poets and scholar-officials. King Sejong recognized that the Chinese writing system, which was used at the time for all government business, was inappropriate for the sounds of Korean; furthermore, he believed it was important to convey the spoken language in writing. King Sejong invented the Korean script (called han’gul or "Korean writing," since about 1913), in late 1443 or early 1444.

These volumes are a tangible legacy of two related seminal historical and cultural events. The poem itself was composed to celebrate the legitimacy of the Chosŏn dynasty, which lasted from 1392 until 1910. In the history of Korean culture, it was a kind of declaration of cultural independence. The invention of a true alphabet that represents the sounds of the Korean language had enormous implications for the development of a national literature, and ultimately national consciousness. The history of printing in Korea, the most advanced in East Asia in the fifteenth century, is also illustrated by this first printing of han’gul.