Their purpose can be made clear. Alternate translation: "a people is coming to attack you" or "an army is coming" (See: [[rc://en/ta/man/translate/figs-explicit]])
Here "nation" represents the army of the nation. Alternate translation: "the army of a great nation" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
Being "stirred up" represents preparing to do something. Alternate translation: "is being prepared to come from a distant land" (See: [[rc://en/ta/man/translate/figs-metaphor]])