lowlands

low|lands /l'oʊləndz/
also lowland
The form lowland is also used as a modifier.
[N-PLURAL] usu the N
Lowlands are an area of low, flat land.
...wherever you travel in the lowlands of the United Kingdom.
...the fever-haunted old town on the lowland across the lake.
...lowland areas.
≠ uplands