Ruins of Desert Cathay 181 - Ruin of ancient watch-tower T.iv c, on western flank of Tun-huang limes with view to north - On left an eroded clay terrace with deep cut Nullah. Across depression with Toghraks and tamarisks is seen in distance an isolated clay terrace (A) bearing remains of ruined watch-tower, T iv a. - Two more of the series of towers to south west of the end of the Han Dynasty wall.