One hypothesis is that the word 아사달 is a compound composed of two elements, asa + dal; this hypothesis is primarily motivated by an assumption of equivalence between the Chinese phonetic transcription 阿斯達 Asīdá and the word 조선 Joseon (朝鮮, Cháoxiǎn or Cháoxiān, in Chinese), another name for Korea.
In fact, up until the Yamato Kingdom changed its name from "Wakoku (倭国)" to "Nihon (日本)", Ancient Korean kingdoms such as Baekje had used the same characters "日本", literally meaning "Land where the sun rises" (no relations to Japan) when it colloquially addressed itself, seeming to have carried over the meaning of "Morning Land" from Asadal.
The first Korean historical work that mention Asadal is the Samguk yusa, which cites the Chinese Book of Wei.
The Samguk yusa also cites the lost historical records of Go-gi (고기; 古記; lit.
But recent studies show that there were more than one city named Pyongyang (which literally means "flat soil" in Chinese), situated in the north deep in Manchuria - possibly bordering in between China and Russia.