It possibly comes from the name of a region called Kwannedo (관내도; 關內道), which was west (서; 西; sŏ) of the Seoul capital area and developed during the Goryeo period.

[2] It was inhabited by the Yemaek, a Proto-Koreanic ethnic group hailing from southern Manchuria.

Kojoson at its height held much of the northern half of the Korean Peninsula, and its capital was Wanggŏmsŏng (present-day Pyongyang, North Korea).

[citation needed] In this case, Pyong’an was named by taking the first syllable from its two principal cities: Pyongyang and Anju.

People in the Kwansŏ region speak the Northwest Dialect (서북 방언, Sŏbuk-pang'ŏn).