From its headwaters below the Kunzum La pass, the River Spiti runs 130km southeast to within the flick of a yak’s tail of the border with Tibet, where it meets the Sutlej. The valley itself, surrounded by huge peaks with an average altitude of 4500m, is one of the highest and most remote inhabited places on earth – a desolate, barren tract scattered with tiny mud-and-timber hamlets and lonely lamaseries. Until 1992, Spiti in its entirety lay off-limits to foreign tourists. Now, only its far southeastern corner falls within the Inner Line – which leaves upper Spiti, including the district headquarters Kaza, freely accessible from the northwest via Lahaul. If you are really keen to complete the loop through the restricted area to or from Kinnaur, you will need a permit. The last main stop before reaching the restricted zone is the famed Tabo gompa, which harbours some of the oldest and most exquisite Buddhist art in the world.