The ‘Aprok’ river(鴨綠江), which appeared in the relationship with Jurchen(女眞) during the early days of the Goryeo dynasty, is the river locating in the northeast. It couldn't be established in the 'Uiju Aprok River' that Goryeo expel led Jurchen toward the northern of the Aprok river to outside the Baekdusan Mountain. The Aprok river was the boundary that Goryeo agreed on with Jurchen and by applying it to the northeast, the 'Hwa-ju Aprok River' emerged as a result. This place is now identified as the upstream of 'Yong-heung river' and was no longer used as it lost the meaning and role of the boundary after the Great wall of Goryeo(長城) was constructed.
Meanwhile, there is a record in The Heritage of the Three States(三國遺事) that 'Yosu(遼水)' was also called as 'Aprok(鴨綠)'. After the war between Khitan and Goryeo, Goryeo established the Aprok River as the boundary of its own northern territory. However, with the fall of Jin dynasty(金), as Goryeo was reigned under Mongol's authority, the meaning of the Aprok river as the boundary was diminished. In response, Goryeo claimed to the perceptions of its own territory about the ‘Yodong’ district. In order to coexist Yoha(Liao-ho, 遼河) as a new boundary with the existing boundary of the Aprok river, Goryeo made the consciousness that Yoha is the Aprok river. However this consciousness was extinct when Yodong district belonged to the Ming(明) dynasty.