Nullahs were nowhere

Nullah: A ravine or gully in southern Asia.

The Yuen Long Nullah is a river in Hong Kong, China.

Null: from Latin 'nullus' - zero, nothing.

Mullahs / Nullahs - master of nothing ('mawla' means 'master' in Arabic). They were also 'nowhere'. HCE / Finnegan is a master of nothing because he is asleep in "nonland" - "Methought as I was dropping asleep somepart in nonland of where's please..." [3:12 403.23] (where's place?).