Later, a larger triangle was drawn connecting Yanji, Cheongjin, and Vladivostok (also Nakhodka), which was called the
Tumen River Economic Development Area (TREDA).
In May 1995, representatives of China, Russia and North Korea initiated the Agreement on the Establishment of the Tumen River Area Development Coordination Committee and, along with Mongolia and South Korea, signed the Agreement on the Establishment of the Consultative Commission for the Development of the
Tumen River Economic Development Area and Northeast Asia, as well as the Memorandum of Understanding on Environmental Principles Governing the
Tumen River Economic Development Area and Northeast Asia.
The geographical definition of
Tumen River Economic Development Area (TREDA) in this paper is a triangle connecting Vladivostok in Primorski Krai, Chonjing in the Democratic People's Republic of Korea (DPRK), and Yanji in the Jilin Province, People's Republic of China.