- Are Italy and Greece “sub-Nordic” ? -- Yes
- Are the U.S. and Mexico “sub-Canadian”? -- Yes
- Is Latin America sub-Anglo-America ? -- No, it would be sub-North American.
Anglo, would be a geographic designation if it were referring to the British Isles (Angla being Latin for England). But, if you're using it to describe North America, then you're implying that North America is wholly or mostly peopled with persons of British ancestory (a false implication).
The Sahara is a geographical location and in no ways implies ethnicity.