Where does “ならば” come from?

ならば (Japanese) comes from Japanese ば, from Japanese は, from Old Japanese は.

ならば (Japanese): if

Definitions

Step	Language	Word	Meaning
1	Japanese	ば	In Modern Japanese, attaches to the kateikei, and...
2	Japanese	は	what about, where is; Inserted between two verbs...
3	Old Japanese	は	—