The kingdom of lazy, jobless people. See "hoboes". Not a real place...because bums are poor and live wherever. More of a metaphoric place.
Bourne quit his job. We welcomed him back to the bumdom.
a bumdom is the favourite spot that a hobo chooses to sleep in.
tom:look at that doorstep covered in piss, vomit, blood and alcohol
dick:oh yes, quite disgusting
harry:oh thats hobo jimmy's bumdom