Triads in the United Kingdom first appeared during the post-World War era with the 14K Triad emerging in Chinese communities in London, Birmingham, Liverpool and Manchester in England and Glasgow, Edinburgh and Dundee in Scotland as early as 1952.
 A later migration followed as members of Chung Mon's organization fled Amsterdam following the Triad leader's death in 1975 as well as those from Hong Kong during the 1980s.
Wo Shing Wo or WSW () is the oldest of the Wo Group triad societies, and is the triad with the longest history in Hong Kong.
 According to the Hong Kong police, the triad is involved in extortion, drug trafficking, gambling and prostitution.
The 14K (十四K) is a triad group based in Hong Kong but active internationally.
 It is the second largest Triad group in the world with around 25,000 members split into thirty subgroups.
 They are the main rival of the Sun Yee On, which is the largest Triad.
The Young and Dangerous film series () is a collection of Hong Kong films about a group of triad young members, detailing their adventures, dangers and growth in a Hong Kong triad society.
 The series is based on a popular comic book series known as "Teddy Boy".
Sun Yee On, or New Righteousness and Peace Commercial and Industrial Guild, is one of the leading triads in Hong Kong and China.
 It has more than 55,000 members worldwide.
The Ping On triad was a Boston-based criminal organization.
 The organization rose to power in the 1970s and continued to operate throughout the 1980s, 1990s and early 2000s.
 The Ping On was founded by Stephen "Sky Dragon" Tse who had heavy ties to the infamous 14K Triad in Hong Kong.
Wo Hop To, or WHT (和合圖) is a Triad group based in Wanchai, Hong Kong.
 The name translates to "Harmoniously United Association" or "Harmonious Union Plan" and is thought to have been founded in 1908 in Sai Ying Pun as a secret political organisation in opposition to the Qing dynasty.
 They are one of the Four Major Gangs (四大黑幫) of Hong Kong, the others being Wo Shing Wo, 14K and Sun Yee On.
Wan Kuok-koi (尹國駒; Cantonese: Wan Gwok-keui; Mandarin: Yǐn Guójū, born 1955), popularly known as Broken Tooth Koi (崩牙駒; Cantonese: bung nga keui; Mandarin: bēng yá jū), was, until his arrest, the leader of the Macau branch of the 14K Triad.
 He was released after more than 14 years in prison on 1 December 2012.
Michael Chan Wai-man (; born 10 July 1946) is a Hong Kong actor.
 A Hakka of Wuhua ancestry born in New Territories, Chan was well known for various triad roles, when in actuality he had been involved with triads in real life.
 In a media interview, he admitted to have been the No. 2 the 14K Triad that dominated vice in Tsim Sha Tsui before the handover of Hong Kong.
 Having worked as a police officer in the prison system, he came into contact with many underworld figures and joined the Triads.
 Chan was expelled from the police force as a result of his links.
Election 2 (literal title: "Black Society: Harmony is a Virtue"), also known as Triad Election in the United States, is a 2006 Category III Hong Kong crime film directed by Johnnie To with a large ensemble cast that includes Louis Koo, Simon Yam and Nick Cheung.
 A sequel to the 2005 film "Election", the film concludes the events of the first film centring on Lok (Yam), who this time struggles to keep his title as triad boss as a triad re-election draws near, while Jimmy (Koo) attempts to retire as a triad to become a legitimate businessman.

Question: What is the name of this triad in Hong Kong in China with tens of thousands of members that rival 14K Triad?
Answer: Sun Yee On