“The Kaesong Industrial Complex, which lies just inside North Korea, is home to 123 South Korean factories which employ more than 50,000 North Korean workers.
It is the last functioning inter-Korean joint project and a key source of revenue for Pyongyang.
North and South Korean officials have reached an agreement about re-opening the Kaesong joint industrial zone, officials from Seoul say.”
http://www.bbc.com/news/world-asia-23682218

http://www.bbc.com/news/world-asia-23682218

https://en.wikipedia.org/wiki/Kaesong_Industrial_Region