Where does “まき” come from?

まき (Japanese) comes from Old Japanese 真木, from Old Japanese 木, from Proto-Japonic kəy — tree.

Ancestry of “まき”, step by step

Step	Language	Word	Meaning
1	Old Japanese	真木	—
2	Old Japanese	木	a tree or shrub; wood, timber, lumber; Combining...
3	Proto-Japonic	kəy	tree

まき — Etymology, Origin & Word History | Etymology Explorer