Today, a high -altitude desert, sheltered from the rain-bearing clouds of the Indian monsoon by the barrier of the Great Himalaya, Ladakh was once covered by an extensive lake system, the vestiges of which still exist on its south -east plateaux of Rupshu and Chushul - in drainage basins with evocative names like Tsomoriri, Tsokar, and grandest of all, Pangong-tso. Occasionally, some stray monsoon clouds do find their way over the Himalaya, and lately this seems to be happening with increasing frequency. But the main source of water remains the winter snowfall. Drass, Zanskar and the Suru Valley are the places on the Himalaya's northern flank that receives heavy snow in winter; this feeds the glaciers whose meltwater, carried down by streams, irrigates the fields in summer. For the rest of the places, the snow on the peaks is virtually the only source of water. As the crops grow, the villagers pray not for rain, but for sun to melt the glaciers and liberate their water. Usually their prayers are answered, for the skies are clear and the sun shines for over 300 days in the year.