The first cricket match between colonies was played in 1865, but the game had been played in the Caribbean for almost half a century by then. By 1900, a triangular series was being held between Demerara, Barbados, and Trinidad, but transport between the islands remained the major obstacle to expansion and it wasn't until after the Second World War when air transport became readily available that Jamaica began to play regular games against other islands.
In 1956, British Guiana hosted a four-team knock-out tournament, and this was repeated five years later with the Combined Islands added. But the problems of traveling between the islands made a regular domestic competition unworkable until the advent of cheap and reliable air travel.
Until the Shell Shield (named after Royal Dutch Shell) was launched in 1965-66, there had been games between islands but they were not part of any competition. The five sides which had contested the 1961 knock-out competed in a round-robin league, with two home matches and two away matches. The format and sponsor remained unaltered until 1981-82 when Combined Islands were split after their maiden success the previous year. Until then, Barbados had dominated with nine titles out of 14. Barbados' dominance continued through the 1980s, and in 1986-87 the competition was restructured into two groups with a final. That was short-lived, and the league was back under a new sponsor in 1987-88, and from 1989-90, when Leeward Islands won their first title, no side established a stranglehold.
Tinkering with the format rumbled on, with a final in 1995-96, a ten-match round-robin the following year and then a five-match event after that as no sponsor could be found. In 1998-99 Busta, a soft drink manufacturer, came on board and the format again changed, with a semi-final and final appended to the league matches. The 2000s also had teams from other countries included - as England A, Bangladesh A, India A and Kenya all played - as well as a West Indies B team built around university students. The B side was ditched in 2004-05 and a round-robin format and a one-off final returned.