What is "tiandihui"

The Tiandihui , literally the Society of the Heaven and the Earth, also called Hongmen 洪門, is a Chinese fraternal organization and secretive folk religious sect. As the Tiandihui spread through different counties and provinces, it branched off into many groups and became known by many names, including the Sanhehui. The Hongmen grouping is today more or less synonymous with the whole Tiandihui concept, although the title "Hongmen" is also claimed by some criminal groups.

When the British ruled Hong Kong, all Chinese secret societies were seen as criminal threats and together defined as Triads, although the Hongmen might be said to have differed in its nature from others. The name of the "Three Harmonies Society" (the "Sanhehui" grouping of the Tiandihui) is in fact the source of the term "Triad" that has become synonymous with Chinese organized crime. Because of that heritage, the Tiandihui is sometimes controversial and is illegal in Hong Kong.