Yunnan borders on three countries, Burma, Laos and Vietnam, with a length of 4,060 kilometer boundary line. In Yunnan, the China-Burma boundary line is 1,997 kilometers long, the China-Laos boundary line 710 kilometers, and the China-Vietnam boundary line 1,353 kilometers. Simao Prefecture in Yunnan is connected to all three foreign countries. It is notable that 16 of the 25 ethnic minorities in the Yunnan province also live across the borders in the neighbouring countries or provinces. Ever since the ancient times, close economic and cultural ties have long been established between Southeast Asia and Yunnan.