Where does “Griechentum” come from?

Griechentum (German) comes from German Grieche, from Middle High German krieche, from Old High German chreah, from Proto-West Germanic krēk, from Latin Graecus, from Ancient Greek Γραικός, from Ancient Greek γραῖα, from Proto-Indo-European ǵerh₂- — to grow old, to mature.

Griechentum (German): the culture, history, religion, and traditions of the ancient and modern Greek peoples

Definitions

the culture, history, religion, and traditions of the ancient and modern Greek peoples

Ancestry of “Griechentum”, step by step

Step	Language	Word	Meaning
1	German	Grieche	a Greek
2	Middle High German	krieche	—
3	Old High German	chreah	—
4	Proto-West Germanic	krēk	Greek
5	Latin	Graecus	Greek, Grecian, of or pertaining to the Greek...
6	Ancient Greek	Γραικός	Greek; a Graecian, a member of an ancient...
7	Ancient Greek	γραῖα	Graea, Boeotia; Greece
8	Proto-Indo-European	ǵerh₂-	to grow old, to mature

Every word from Proto-Indo-European ǵerh₂- →Every word from Ancient Greek γραῖα →Every word from Ancient Greek Γραικός →