Wallacea is named for Alfred Russel Wallace, British nautralist (1823-1913), who came up with the idea of evolution independently of Charles Darwin. He discovered the Wallace Line, beyond which marsupial mammals dominated (as opposed to placental mammals on the near side of the line)--mainly New Guinea and Australia.
It looked to me that the Wallace line was about 1/2 way between mainland Asia and mainland Australasia (to use a British term for the continent).
Most atlases put all of the West Indies in North America (I found one that put Trinidad & Tobago in South America).
Their version of the Wallace line would put most of the Greater Antilles in North America and most of the Lesser Antilles in South America.
A number of Greek islands are closer to mainland Asia than they are to mainland Europe.