Over 2 million ethnic Koreans live in China, and this area has a large concentration of them. While there are some expatriates from North and South Korea, most of the ethnic Koreans here hold Chinese citizenship, making it the largest ethnic Korean community outside Korea.
Korean is co-official in this area, along with Mandarin Chinese due to the large number of ethnic Koreans. The dialect of Korean spoken here is the Hamgyong dialect, which is also spoken in Hamgyong province in North Korea, and is slightly different from the Seoul dialect which is standard in South Korea, or the Pyongan dialect which is standard in North Korea. Most younger ethnic Koreans in this area are bilingual in Korean and Mandarin, so Mandarin speakers should not have any problems communicating.
All official signs, as well as most restaurant menus in the area are bilingual in Korean and Mandarin.