Where does “Pireu” come from?

Pireu (Portuguese) comes from Ancient Greek Πειραιεύς, from Ancient Greek πέρα, from Proto-Indo-European per-, from Proto-Indo-European pr̥tós — passed , crossed.

Ancestry of “Pireu”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Πειραιεύς	Piraeus, Athens, Attica, Greece
2	Ancient Greek	πέρα	beyond
3	Proto-Indo-European	per-	before, in front; first; to go through
4	Proto-Indo-European	pr̥tós	passed , crossed

Every word from Proto-Indo-European pr̥tós →Every word from Proto-Indo-European per- →Every word from Ancient Greek πέρα →