The length of the Copper Age is 2,000 divine years, equal to 720,000 human years, while its Twilight periods are 72,000 years each. Men in this age are seven cubits or ten and a half feet high. Virtue lives in it in two quarters, the other two being filled by vice. Vitality is rooted in the blood; men live as long as there is blood in their body. Gold and silver leaving become dearer the metal generally used in making household utensils is copper which is found abundantly, whence the age derives its name. The intensity of accelerated Rāja within Nature helps the assertion of Tama in all her manifest phases, although Sattwa still has some influence. The trees become less in height, less fruitful and the fruits less sweet; crops less abundant despite the best efforts of cultivation. Cows give less milk than in the Silver Age, while wild animals become more ferocious. Most animals can speak in the Silver Age, but now only some of them, the higher ones, are blessed with that power during the major portion of it. People in the Copper Age become more and more outward-looking generally, especially the Sudras, some of whom having become filled with dense Tama, revolt against all laws and discipline and turn into thieves and robbers. These latter are expelled from their caste and banished out of civilized centres of population the world over by the kings. They are called by the common name of robbers and specific names of Yavans and Mlechhas which means men who are wild, barbarous and unclean by nature and habits. These Yavans and Allechhas come into existence towards the end of the Silver Age and rapidly increase in number during the Dwāpar (Copper Age), towards the end of which they form the majority of the world's population and are known by different names according to the localities of their habitation, different shades of their dark attributes, and the callings they pursue: Yavan, Kirāt (hunters), Gāndhār, Cheen (Chinese), Shabar, Barbar (barbarian), Shak, Tungār, Kanka, Palhab, Ramat and Kambhoj. The kings in the Copper Age have a hard time to protect their subjects and their territories from the depredations of these wild characters and robbers. The king's first duty is to preserve peace in his kingdom so that his subjects may not be disturbed in the performance of their religious duties, may apply themselves to the study of the Veda and the contemplation of the Supreme Deity and tread the path of virtue without annoyance.