Land of Nod (everywhere except Eden)

Cain went there a wife to find
His Dad was 900 and his Mother, not sure
He soon found himself in a bind
Because his marriage may not be pure.

They were all brothers and sisters
And of many ages in years
And you either married your sister
Or at best a niece as a peer.

Now it stands to reason that my wife,
Now of the same blood as are all
Is bound to serve with enormous strife
Just as did the mighty Saul.

There were no other tribes you see
So, we are very lucky to even be!