Gong woo gau gap

First I saw a screenshot of this film, and the line below attracted me: I am Ren Yingjiu, among the lawless world(Jiang Hu), and I am Aries. It get me confused that what is an exact explanation to this word "Jiang Hu'', maybe "lawless world" or "underworld". One scene in this film is a police asking Leung Kai Fai what is "Jiang Hu" in English, and Leung never answered but smiled. No one ever knows what "Jiang Hu" is as we never experienced a time like this. It is surprising that this film produced in 2000 should have made such a great wonder. Next time I want to see this film with my boyfriend:), he is Aries as well.