Kali Yuga (Devanāgarī: कलियुग, lit. "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 Indian scriptures. The other ages are Satya Yuga, Treta Yuga and Dvapara Yuga.
The Mahabharata War and the decimation of Yadavas thus happened at the Yuga-Sandhi i.e. the joint of the two yugas.
The scriptures mention Sage Narada to have momentarily intercepted the demon Kali on his way to the Earth when Duryodhana was about to be born...to make him an embodiment of 'arishadvargas' and adharma in preparation of the era of decay in values and the consequent havoc.
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. This date is also considered by many Hindus to be the day that Krishna left Earth to return to his abode.
Most interpreters of Hindu scriptures believe that Earth is currently in Kali Yuga. Other authors such as Swami Sri Yukteswar, and Paramhansa Yogananda believe that it is now Dvapara Yuga. Aurbindo Ghosh has written that Kali Yuga is now over. The Kali Yuga is sometimes thought to last 432,000 years, although other durations have been proposed.
Hindus believe that human civilization degenerates spiritually during the Kali Yuga, which is referred to as the Dark Age because in it people are as far away as possible from God. Hinduism often symbolically represents morality (dharma) as a bull. In Satya Yuga, the first stage of development, the bull has four legs, but in each age morality is reduced by one quarter. By the age of Kali, morality is reduced to only a quarter of that of the golden age, so that the bull of Dharma has only one leg.
Kali Yuga is associated with the apocalyptic demon Kali, not to be confused with the goddess Kālī (read as Kaalee) (these are unrelated words in the Sanskrit language). The "Kali" of Kali Yuga means "strife, discord, quarrel, or contention."
Read more about Kali Yuga: Personification