Where does “Аляксей” come from?

Аляксей (Belarusian) comes from Old East Slavic Алексий, from Ancient Greek Ἀλέξιος, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

Ancestry of “Аляксей”, step by step

Step	Language	Word	Meaning
1	Old East Slavic	Алексий	—
2	Ancient Greek	Ἀλέξιος	helper, defender
3	Ancient Greek	-ῐος	belonging to; of”, “belonging to”, “pertaining to
4	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 Ἀλέξιος →