Appearing in the 17th century in the form of secret societies, the triads gradually evolved into criminal organizations. Western colonization represented a great opportunity for them. After the opium wars, they became involved in the drug trade and grew rich. They became powerful enough to influence the founding of the Republic of China. After World War II, Mao's rise to power forced the triads to leave the country. But they did not go far: to Taiwan and Hong Kong, where they lived their golden years.