Tabaṣṣar is a second-person masculine singular imperative from form V (tabaṣṣara, root b-ṣ-r). Tarā is the imperfect of raʾā, used in the question. Taḥammalna is a third-person feminine plural perfect; its subject is the women in the litters.
The noun after min ẓaʿāʾin is genitive. Bi-l-ʿalyāʾ locates the departure in elevated terrain, and min fawqi Jurthum adds a further spatial marker. Grammar and geography work together.