Kali Yuga or “age of Kali”, or “age of vice” is the last of the four stages the world goes through as part of the cycle of yugas described in the Sanskrit scriptures. The other ages are Satya or Krita Yuga (Golden Age), Treta Yuga (Silver Age) and the Dwapara Yuga (Bronze Age). The Krita Yuga was so named because there was but one religion, and all men were saintly: therefore they were not required to perform religious ceremonies. Men neither bought nor sold; there were no poor and no rich; there was no need to labour, because all that men required was obtained by the power of will. In the Treta Yuga sacrifices began; virtue lessened a quarter. Mankind sought truth and performed religious ceremonies; they obtained what they desired by giving and by doing. In the Dwapara Yuga, religion lessened one-half. The Veda was divided into four parts, and although some had knowledge of the four Vedas, others knew but three or one. Mind lessened, Truth declined, and there came desire and diseases and calamities; because of these men had to undergo penances. It was a decadent Age by reason of the prevalence of sin.
The duration and chronological starting point in human history of Kali Yuga has given rise to different evaluations and interpretations. According to the Surya Siddhanta, Kali Yuga began at midnight (00:00) on 18 February 3102 BCE in the proleptic Julian calendar, or 14 January 3102 BC in the proleptic Gregorian calendar. It is supposed to have started thirty-five years after the conclusion of the great battle of the Mahabharata. This date is also considered by many Hindus to be the day that Lord Krishna left Earth to return to his abode.
The Kali Yuga is sometimes thought to last 432,000 years, although other durations like 1200 years have been proposed. Hindus believe that human civilization degenerates spiritually during the Kali Yuga because in it people are as far away as possible from God.