I've stumbled upon some websites about Hakka people （客家人--sounds like "hag4 ga2 ngin3" in Hakka）recently. Anyway, there were some rather interesting articles. I'll share some of them here:

The only state that the Hakka people ever possessed was the Lan Fang Republic. Kwangtung Hakkas briefly established a Hakka state in Western Kalimantan in 1777 and lasted until 1884. The first of ten presidents was Low Lan Pak, a Meixian Hakka. In 1884 the Dutch attacked the republic and after 4 years of battle the Hakkas were defeated and fled to Sumatra. From there they moved to Kuala Lumpur and Singapore where they contributed significantly to the establishment of the state of Singapore. The capital of this Lan Fang Republic is a place now known as Pontianak (vampire!).

Famous Hakka people include Sun Yat-Sen, Yap Ah Loy and Lee Kuan Yew.

The Hakka dialects are one of the oldest languages of China and constitute one of the seven major language groups of Chinese. The language is very similar to the official language spoken in the Tang dynasty (618-907 A.D.). The Hakka language is also referred to as Hak-fa, Hak-ka-wa, K'ak-wa, or Makkai-wa.

This website gave lots of info: http://www.asiawind.com/hakka