Asaph speaks of "regions" as if they were containers in which one could put "places of violence." Alternate translation: "violent people do evil deeds in dark places in the land wherever they can" (See: [[rc://en/ta/man/translate/figs-metaphor]])
The word "dark" is probably a metaphor for a place where bad things happen or for the lands to which the Israelites had been sent in exile, but these words should be translated literally if possible. (See: [[rc://en/ta/man/translate/figs-metaphor]])