Korean has several dialects (called mal [literally "speech"], bang-eon, or saturi in Korean). The standard language (pyojuneo or pyojunmal) of South Korea is based on the dialect of the area around Seoul, and the standard for North Korea is based on the dialect spoken around P'yŏngyang. These dialects are similar, and are in fact all mutually intelligible, except the dialect of Jeju Island (see Jeju Dialect). The dialect spoken in Jeju is classified as a different language by some Korean linguists. One of the most notable differences between dialects is the use of stress: speakers of Seoul dialect use stress very little, and standard South Korean has a very flat intonation; on the other hand, speakers of Gyeongsang dialect have a very pronounced intonation.
It is also worth noting that there is substantial evidence for a history of extensive dialect levelling, or even convergent evolution or intermixture of two or more originally distinct linguistic stocks, within the Korean language and its dialects. Many Korean dialects have basic vocabulary that is etymologically distinct from vocabulary of identical meaning in Standard Korean or other dialects, such as South Jeolla dialect /kur/ vs. Standard Korean /ip/ "mouth" or Gyeongsang dialect /ʨʌŋ.gu.ʥi/ vs. Standard Korean /puːʨʰu/ "garlic chives." This suggests that the Korean Peninsula may have at one time been much more linguistically diverse than it is at present. See also the Buyeo languages hypothesis.
There is a very close connection between the dialects of Korean and the regions of Korea, since the boundaries of both are largely determined by mountains and seas. Here is a list of traditional dialect names and locations:
Standard dialect Where used
Seoul Seoul, Incheon, Gyeonggi (South Korea); Kaesŏng (North Korea)
P'yŏngan P'yŏngyang, P'yŏngan region, Chagang (North Korea)
Regional dialect Where used
Chungcheong Daejeon, Chungcheong region (South Korea)
Gangwon Gangwon-do (South Korea)/Kangwŏn (North Korea)
Gyeongsang Busan, Daegu, Ulsan, Gyeongsang region (South Korea)
Hamgyŏng Rasŏn, Hamgyŏng region, Ryanggang (North Korea)
Hwanghae Hwanghae region (North Korea)
Jeju Jeju Island/Province (South Korea)