A separate theory states that the group originated in Mongolia. One of the main supporters of this belief, Clyde Kiang (江運貴), a professor of library science at California University of Pennsylvania (in California, Pennsylvania), supports his view with a recent Japanese report on DNA that links the Japanese, Koreans, and Hakka with Mongolians. Kiang also stresses similarities between the group's dialect and the Altaic language family.
The dispute over Hakka origins results from the group's 1,500-year history of migration, a tradition that earned them the nickname "gypsies of China." According to the most widely held theory, supported by both Chen and another leading Hakka expert, Luo Hsiang-lin (羅香林), the group experienced five large-scale migrations. The first took place during the final years of the Chin dynasty (265-420), after the warfare against the foreign invaders of northern China. At this time, a large number of Han royalty fled from the city of Changan in Shensi province, the Chin capital city, to the southern provinces of Hupeh, Honan, Anhuei, and Kiangsi.
The second migration began when the Huang Chao Rebellion (874-884) forced the Hakka settled in the south to move again. This time, they fled to southern Anhuei, southeast Kiangsi, southwest Fukien, and northeast Kwangtung. The third relocation took place during the Mongol invasion that swept through much of the country in the final years of the Southern Sung dynasty (1127-1279). Many of these immigrants moved to northern and eastern Kwangtung province and even headed overseas to Southeast Asian countries.
When these Hakka swarmed into the south with their strange language and northern customs, they were not welcomed. In Kwangtung, they were forced to settle in the less fertile uplands. There, they formed tight-knit communities and never became fully assimilated into the native population.
In the south, according to Chen Yun-tung, the class differences among the various Hakka groups faded with time. "With each migration, the prestigious Hakka gradually lost their position and their property," Chen says. Oftentimes, Hakka families had to let their servants go in order to survive. "These former servants, now living independently, carried on the customs and habits of their masters," says Chen. "Gradually, class distinctions among the Hakka diminished." Over time, local residents began to regard the Hakka as a distinct ethnic group, and Kwangtung province became their homeland.
During the early Ching dynasty (1644-1911), the combination of population pressures, a shortage of farmland, and the desire to escape from the oppressive Ching rulers spurred many Chinese to seek a new life outside China. The Hakka's fourth major migration was part of this movement. Most of the Hakka who left were from the southern coastal provinces of Fukien and Kwangtung. Some moved into the center and coastal areas of Kwangtung, or to Kwangsi, Hunan, and Szechuan provinces, but many went to Taiwan, Southeast Asia, and as far away as Africa and the Caribbean.
The Taiping Rebellion (1850-1864) against the Ching royalty, led by Hakka, set off the final large-scale migration. The rebellion began in southern China when Hakka rebels instigated an uprising against the government. By some estimates, as many as 20 million people were killed during the fifteen years of warfare. When it ended in a loss for the rebels, thousands of Hakka sailed to Hainan Island, Southeast Asia, and Taiwan—beginning a new chapter in their history as newcomers and guests.