Hakka history, based largely on genealogical evidence and other historical records, as well as linguistic evidence, support and substantiate Hakka claims to northern Chinese origins. In the People's Republic of China the Hakka are officially included in the category of Han Chinese.
The Hakka have had a long history of conflict and competition with other Chinese groups over scarce land and resources. In Fujian and Taiwan they suffered from hostile relations with Min, and in Guangdong they fought with Yue speakers. Hakka-Yue conflicts were particularly violent throughout the middle of the nineteenth century, in the aftermath of the Taiping Rebellion, and during the Hakka-Bendi Wars (1854-1867).
Today most Hakka and non-Hakka scholars agree that the ancestors of those who later became known as "Hakka" were Chinese who came from southern Shanxi, Henan, and Anhui in north-central China.
From the "cradle of Chinese civilization," these proto-Hakka gradually moved southward in five successive waves of migration. Historians do not agree, however, on the exact time and sequence of the earliest migrations.
Most historians place the first migration during the fourth century at the fall of the Western Jin dynasty, when Hakka ancestors reached as far south as Hubei, south Henan, and central Jiangxi.
The next period is less debated. By the late ninth and early tenth centuries, with the disorder created during the late Tang dynasty, the ancestors of the present-day Hakka moved farther south into Jiangxi, Fujian, and Guangdong.
The third wave, which stretched from the beginning of the twelfth century to the middle of the seventeenth, was caused by the exodus of the Southern Song dynasty and their supporters in a southward flight from the Mongol invasion. This dislodged people from Jiangxi and southwestern Fujian and forced them further into the northern and eastern quarters of Guangdong. By the end of the Yuan dynasty (A.D. 1368), northern and eastern Guangdong were exclusively Hakka.
The fourth wave, which lasted from the mid-seventeenth century to the mid-nineteenth century, began with the Manchu conquest, and during the Qing dynasty, migration expanded into the central and coastal areas of Guangdong, Sichuan, Guangxi, Hunan, Taiwan, and southern Guizhou.
By the time of the fifth wave, beginning at the middle of the nineteenth century, conflicts between the Hakka and the Yue increased. Triggered by population pressure, the Hakka-Bendi (Yue) Wars, and the large Hakka involvement in the Taiping Rebellion, the fifth wave of migration sent Hakka emigrants to seek better lives farther afield—to the southern part of Guangdong, to Hainan Island, and overseas to Southeast Asia (especially Malaya and Borneo).
The establishment of the People's Republic of China and China's announcement of the intent to reclaim Hong Kong in 1997 have created what might be called the sixth wave of migration, which has continued the flow of Hakka overseas, especially to the United States, Australia, and Canada.
source:
http://www.everyculture.com/Russia-Eurasia-China/Hakka-History-and-Cultural-Relations.html
