As the mountainous area is mostly on the eastern part of the peninsula, the most crucial rivers are likely to stream westwards. Two exceptions are classified as the southward-flowing Nakdong River and Seomjin River.

But the Sui Military was lured into a entice with the famed Koguryŏ commander Ŭlchi Mundŏk, and suffered a calamitous defeat for the Salsu (Ch'ŏngch'ŏn) River. It is claimed that only 2,seven-hundred in the 300,000 Sui troopers who had crossed the Yalu survived to search out their way back again, as well as Sui emperor now lifted the siege of Liao-tung Fortress 파라곤솔루션 and withdrew his forces to China suitable. Yang Ti continued to send out his armies towards Koguryŏ but all over again with no achievement, and in advance of extended his war-weakened empire crumbled." ^