The southeast corner of Russian Turkestan was the high Pamirs which is now the Gorno-Badakhshan Autonomous Region of Tajikistan. The high plateaus on the east are used for summer pasture. On the west side difficult gorges run down to the Panj river and Bactria. In 1871 Alexei Pavlovich Fedchenko got the Khan's permission to explore southward. He reached the Alay Valley but his escort would not permit him to go south onto the Pamir plateau. In 1876 Skobelev chased a rebel south to the Alay Valley and Kostenko went over the Kyzylart Pass and mapped the area around Karakul Lake on the northeast part of the plateau. In the next 20 years most of the area was mapped. In 1891 the Russians informed Francis Younghusband that he was on their territory and later escorted a Lieutenant Davidson out of the area ('Pamir Incident'). In 1892 a battalion of Russians under Mikhail Ionov entered the area and camped near the present Murghab, Tajikistan in the northeast. Next year they built a proper fort there (Pamirskiy Post). In 1895 their base was moved west to Khorog facing the Afghans. In 1893 the Durand Line established the Wakhan Corridor between the Russian Pamirs and British India.