The Central Asian republics of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan cover an area of approximately 4 million square kilometres. Kazakhstan alone is roughly four-fifths the size of India, with a total area of 2,717,300 square kilometres. The natural barriers which encompass this vast territory include great mountain ranges such as the Tien Shan or Heavenly Mountains in the east, the Pamirs in the south-east and the Altai range in the north-east. In the west, the Caspian Sea provides a border between Central Asia and the Caucasus. The expansive steppe in the north, with its extreme continental temperatures, combined with the Kara Kum and Kyzl Kum deserts, in the central and southern regions, have consistently been an obstacle to penetration throughout history.