Numerous tours have occurred throughout history and have been mostly carried out by the top three rugby league nations Australia (Kangaroos), Great Britain (Lions), and New Zealand (All Blacks/Kiwis).
Tours historically consisted of a number of non-test matches against club or composite teams and single-match tests against national sides, before a three-game test series against the national side of the tour's primary destination.
These three-game test series were the primary event of the tours and would often be their own competition, the most famous being The Ashes.
More modern tours have often skipped non-test matches to play only the "primary event".
Prior to 1954 and the first Rugby League World Cup, tours were the main form of international competition in the sport.