Hakka is one dialect of the Chinese language. It has approximately thirty-three million speakers world wide. However, there are sub-dialects of Hakka. This is due to the geographical distribution and local influences on its speakers. The Moi Yen (Meixian) dialect is considered to be the standard dialect. Meixian is a city in the north eastern region of Guandong Province in China. Other sub-dialects of Hakka differ tonally and phonetically. They are grouped together as Hakka because they all share a common vocabulary and many other features.
The term 'Hakka' or 'Hak Ga' comprises of two words, meaning, Hak='guest' and Ga='family'. The term 'guest families' referw to the Hakka people because of documented evidence of a history of migration. Studies of family genealogies show that the ancestors of the original Hakka, were residents of the Great Central Plains of Eastern China, around the Yellow River basin about two millenia ago.
Due to various threats of war and other influences, the Hakka fled in five great exoduses. The first of these began with an invasion of non-Chinese from the north into the plains, creating the turbulent period of Chinese history known as the Sixteen States. Towards the end of the Tang Dynasty, the country had become riddled with corruption and bad government. The threat of war triggered yet another wave of population movement. The Mongol conquest of China, in the middle of the thirteenth century, caused the Hakka flee south again. A fourth wave happened with the collapse of the Ming dynasty. China, this time, was conquered by another non-Chinese invader, the Manchu, who formed the Qing Dynasty. Towards the end of the 1830's unrest (Taiping Rebellion) lead by a fiery Hakka christian preacher, lead to the establishment of the 'Da Ping Tian Guo' or Great Kingdom of Heavenly Peace, rivalling the Manchu Qing government. It lasted about fifty years and weakened when its leader died. Squabbles in the leadership then caused the kingdom to collapse and the Qing government ruthlessly persued its one time followers. Hence the fifth great movement occurred.
We can add a new wave of Hakka dispersion, this time to places outside Asia. Many migrants found manual work in America to the end of the nineteenth century. In more recent times, people have moved to Europe to build businesses in catering, the cliché chinese restaurant or take-away. They have set up roots in their new country of choice, some into their third or fourth generations. Those pioneers are called Lao Fa Kiao or Old Chinese Abroad. And their decendents see themselves as chinese, because they have strong ties to their roots and bound by a common language.