A thorough look at the meaning and grammar of "reichen" and what "handing" has to do with "being enough" and "areas".
reichen, ausreichen, erreichen, der Bereich, hinreichend, ausreichend
The core idea of this root was:
stretching out, reaching out, stiffening
A good mental image is reaching out the arm.
It’s the origin of reach and reichen as well as the words rigor and rigid.