His fourth journey in 1883-1885 was to Sining (the great trade centre of the Chinese borderland), and thence through northern Tibet (crossing the Altyn Tagh to Lop Nor), and by the Cherchen-Keriya trade route to Khotan.
The names given to them are the Kilian or Kiliang, the Khotan and the Keriya Mountains in the more northerly range and the Raskem or Raskan, the Sughet and the Ullugh-tagh Mountains in the more southerly range.
From the transverse breach of the Keriya-darya (about 811° E.) to that of the Kara-muren in the longitude of Cherchen (about 852° E.) the parallel border-ranges of the Tibetan plateau trend to the E.N.E., and here occur in the lower or outer range the passes of Dalai-kurghan-art (14,290 ft.), Choka-davan, i.e.
Kargalik, Khotan, Keriya, Niya, Cherchen, Charkhlik, Sa-chou, and An-hsi-chou, but these settlements, some of them of very great antiquity, have to maintain a constant fight against the encroachments of the desert sand.
The principal towns and their populations are Yarkand, 100,000; Khotan, 40,000; Kashgar, 33,000; Ak-su, 15,000; Keriya, 12,000; and Kulja, 20,000.
At the same time the same explorer excavated part of the ruins of the ancient city of Takla-makan (near the Keriya-darya), which had been overwhelmed by the moving sands of the desert.
(iii.)At Niya, east of Keriya, where many Kharoshti documents on wood were `recovered, sometimes retaining their clay seals of Greek type and wooden covers as envelopes, together with implements, furniture, &c. (iv.)At Miran, near the western extremity of Lop-nor, where Buddhist shrines with frescoes, &c., were investigated.