Where does “Αττική” come from?

Αττική (Greek) comes from Ancient Greek Ἀττική, from Ancient Greek Ἀττικός, from Ancient Greek -ικός, from Ancient Greek -κός, from Proto-Indo-European -ḱos — -y, -ic.

Ancestry of “Αττική”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Ἀττική	Attica
2	Ancient Greek	Ἀττικός	Attic, Athenian
3	Ancient Greek	-ικός	of or pertaining to, in the manner of; -ic
4	Ancient Greek	-κός	forms adjectives with the sense of 'of or...
5	Proto-Indo-European	-ḱos	-y, -ic

Every word from Proto-Indo-European -ḱos →Every word from Ancient Greek -ικός →Every word from Ancient Greek -κός →