As a non-native speaker, I don't think I've ever seen this expression, but one can easily guess what it means. Enumerating bits of the whole as a way to emphasi

As a non-native speaker, I don't think I've ever seen this expression, but one can easily guess what it means. Enumerating bits of the whole as a way to emphasize the wholeness, I think, might be common in many languages. Regarding mainland Asia, I just understand it as "not island" Asia.