meanwhile, however, the former western liang general tang qi (唐契) was attacking another former northern liang general, hei shuang (闞爽), at gaochang. hei sought help from juqu wuhui, but as juqu wuhui arrived with aid, hei had already killed tang in battle and refused to grant juqu wuhui admission. in fall 442, juqu wuhui made a surprise attack on gaochang, capturing it, and hei fled to rouran. juqu wuhui moved his headquarters to gaochang, and sent messengers to liu song's capital jiankang, submitting as a vassal and seeking an alliance. emperor wen of liu song created him the prince of hexi.