Qinghai, Yumenguan, Loulan
The fourth is the snow-capped mountains, that is, the Qilian Mountains stretching across the south of the Hexi Corridor
In poetry, only "snow-capped mountains" have no clear meaning Out of place name.
Snow Mountain - Qilian Mountains
The place names in the order of ancient poetry are: Qinghai, Snow Mountain (Qilian Mountain), Yumen Pass, Loulan (ancient city)
The fourth should be Loulan ancient city