On the west East Turkestan is generally approached from India by the famous pass of Karakorum (18,300 ft.), from Ferghana and West (Russian) Turkestan by the passes of Kyzyl-art (14,015 ft.) and Terek (12,730 ft.), and 'the mountains on this side attain to altitudes of 25,780 ft.
Yarkand and Khotan communicate with India over the lofty pass of Karakorum (18,300 ft.) and through Leh in Ladak, and thence over the difficult pass of Zoji-la (11,500 ft.).
The latter range is separated from the Karakorum Mountains by the deeply trenched gorge of the Raskem or Yarkand-darya, while the deep glen of the Kara-kash or Khotan-darya intervenes between the upper (Sughet Mountains) and the lower (Kilian Mountains) border-ranges.
Near the upper Orkhon was the permanent camp of Karakorum, from the 8th century down to the end of the 13th the centre of the Mongol power, especially under the sway of Jenghiz Khan and his son Ogotai or Ogdai in the 12th and 13th centuries.
Nothing came of either of these missions; but through them Europe first began to know the interior of Asia, for Carpini was conducted by the Mongols as far as Karakorum, the capital of the great khan, on the borders of China.