This book is concerned with the historical fact of overseas Chinese and ethnic Chinese living in Myanmar, Thailand, Vietnam and Laos before 1949. Against the social background of acute class and ethnic conflicts in Yunnan in modern times, many Chinese people had immigrated. The immigration of overseas Chinese of Yunnan origin was influenced by the condition of transportation. There were economic and political reasons for the immigration, and the former was the chief reason. Myanmar was a preferred destination for emigration. The Chinese immigrants of Yunnan origin there were mainly engaged in business and mining, supplemented by agriculture and handicraft. Overseas Chinese received different treatments by different countries in different periods: sometimes they were well-received and accepted, while sometimes isolated, suppressed, and cracked down. Overseas Chinese had made indelible contributions to the agriculture, industry, commerce, culture, and education in both their adopted homeland and their country of origin. In the Ming and Qing Dynasties and the Republic of China, the central government and the local government of Yunnan implemented different overseas Chinese policies. The overseas Chinese policy of the Yunnan government in the Republican Era were all in all a success. They were a foundation of the overseas Chinese policy adopted by the government of the People's Republic of China.