。
Dusk enveloped the desert.
Literal
Dusk [subject-が] desert [object-を] envelop-[past-んだ].
Another cinematic line. 包む ('to wrap, envelop, wrap around') is a tactile-feeling verb — often used metaphorically for atmosphere or feeling enveloping a place or person. Paired with an abstract subject like 夕闇, it conveys the scene being gradually overtaken by darkness. A sentence you might find in a novel's opening.