Complete books of South Korea's oldest surviving history texts have been designated as national treasures.

The Cultural Heritage Administration said Wednesday that two 'Samguk Sagi' books designated were designated as National Treasures Number 322-1 and Number 322-2, respectively. 

The two artifacts include nine finished volumes out of the total 50, which provide essential information on the academic trends and printing conditions of the period between the Goryeo dynasty and the early Joseon dynasty. 

The Samguk Sagi texts, compiled at a national level in 1145 by Goryeo dynasty scholars, cover the rise and fall of the ancient Silla, Goguryeo and Baekje kingdoms in detail. The texts are considered to have laid the basis for the beginning of the country's historical research. 

Until now, the Samguk Sagi texts were registered as three treasures and one tangible cultural property.