The Southeast Asian Games owes its origins to the South East Asian Peninsula Games or SEAP Games. On 22 May 1958, delegates from the countries in Southeast Asian Peninsula attending the Asian Games in Tokyo, Japan had a meeting and agreed to establish a sport organisation. The SEAP Games was conceptualised by Luang Sukhum Nayaoradit, then Vice-President of the Thailand Olympic Committee. The proposed rationale was that a regional sports event will help promote co-operation, understanding and relations among countries in the Southeast Asian region.
The first SEAP Games were held in Bangkok from 12–17 December 1959 comprising more than 527 athletes and officials from Thailand, Burma, Malaya (now Malaysia), Singapore, South Vietnam and Laos participating in 12 sports.
The 2009 Southeast Asian Games was the first time Laos has ever hosted a Southeast Asian Games (Laos had previously declined hosting the 1965 Southeast Asian Peninsular Games citing financial difficulties). Running from 9–18 December, it has also commemorated the 50 years of the Southeast Asian Games, held in Vientiane, Laos.
Singapore hosted the last SEA Games, which was the 2015 SEA Games. Cambodia has yet to host the SEA Games. At first starting 2019, the Asian Games will fall on the same year as the Southeast Asian Games but Vietnam then declined to host the 2019 Asian Games.
The games is unique in that there are no official limits to the number of sports which may be contested, and the range may be decided by the organising host pending approval by the Southeast Asian Games Federation. Albeit for some core sports which must be featured, the host is also free to drop or introduce other sports.
This leeway has resulted in hosts maximising their medal hauls by dropping sports which are disadvantages to themselves relative to their peers, and the introduction of obscure sports, often at short notice, thus preventing most other nations from building up credible opponents. Some examples of these include:
At the 2007 Southeast Asian Games, Thailand added some new categories of sepak takraw and used a new kind of ball that had been used by their athletes for a year while other countries had never used it before. Futsal was also added. Thailand won nearly all sets of medal from that discipline.