Genesis 4:16

‘And Cain went away from the place of Yahweh, and dwelt in the land of Nod, east of Eden.'

The land of Nod (nod = ‘wandering') refers to the desert, the ‘land of wandering'. Man moves ever onward, eastwards from Eden, driven by sin, getting further and further away from Paradise. Leaving ‘the place of Yahweh' suggests that the writer has in mind that Cain has now lost even that place where food could be obtained, the place that Yahweh had allowed man (the ‘face of the ground'? - v.14). Now he would have to search out for himself whatever he ate.