redoubt
A small, temporary, military fortification.
A reinforced refuge; a fort.
A place of safety or refuge.
To the south, the vast geometrical deserts of Arabian nomads, a redoubt of feral movement, of fickle winds, of open space, of saddle leather—home to the wild Bedouin tribes.
2014, Paul Salopek, Blessed. Cursed. Claimed., National Geographic (December 2014)https://web.archive.org/web/20150212214621/http://ngm.nationalgeographic.com/2014/12/pilgrim-roads/salopek-text
Where it comes from
From French redoute, from Italian ridotta, from Medieval Latin reductus (“refuge”), from Latin redūcō (“to withdraw”), with spelling influenced by doubt.
Adapted from the Wiktionary entry redoubt (CC BY-SA 4.0).