Australia has always been geographically part of Oceania, which is a region that includes Australasia, Melanesia, Micronesia, and Polynesia. The term "Oceania" is used to refer to the collective group of islands and countries in the Pacific Ocean region.
The OED, tells us that the term Pacific Rim first appeared in 1926, and refers to 'the countries and regions which border the Pacific Ocean'.
Countries of the Pacific Rim The "Pacific Rim" includes the countries that lie along the Pacific Ocean. Plus, the island countries of the Pacific
The noun 'countries' is not a collective noun.A collective noun is a noun used to group people or things in a descriptive way; for example, an alliance of countries or a coalition of countries.
Forests, is the collective term for groups of treed vegetation.
The collective term for a group of tortoises is a "creep."
Oceania
Geese is actually the collective term for goose.
Collective Term stands for a group of objects, people, or thing as a basic unit.
The collective term for a group of ferrets is a "a business of ferrets" or "a cast of ferrets".
The noun perianth is a collective term for all the petals and sepals.
AustronesianThe 12 million people living in Oceania, speak numerous Austroneasian languages.