ASEAN countries and Lan Mei countries are two different concepts. ASEAN countries refer to the members of the Association of Southeast Asian Nations, including Brunei, Myanmar and Cambodia 10 countries. These countries have close ties and cooperation in economy, politics and culture.

Lan Mei countries refer to six countries in the Lancang-Mekong River basin, including China, Myanmar, Laos, Thailand, Cambodia and Viet Nam. Lan-Mei cooperation is a new sub-regional cooperation mechanism proposed by China and the five Mekong countries at the first leaders' meeting held on March 23rd, 20th16th, aiming at strengthening cooperation and exchanges among countries in economic, political and cultural fields.