Where does “Maurusia” come from?

Maurusia (English) comes from Latin Maurūsia, from Ancient Greek Μαυρουσία, from Ancient Greek Μαυρούσιος, from Ancient Greek -ούσιος, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

Maurusia (English): Mauretania

Definitions

Mauretania

Ancestry of “Maurusia”, step by step

Step	Language	Word	Meaning
1	Latin	Maurūsia	—
2	Ancient Greek	Μαυρουσία	—
3	Ancient Greek	Μαυρούσιος	an inhabitant of Mauretania; a Mauretanian
4	Ancient Greek	-ούσιος	forms relational adjectives: of or pertaining to
5	Ancient Greek	-ῐος	belonging to; of”, “belonging to”, “pertaining to
6	Proto-Indo-European	-yós	Creates adjectives from noun or verb stems

Every word from Proto-Indo-European -yós →Every word from Ancient Greek -ῐος →Every word from Ancient Greek -ούσιος →