Yuga
In Hinduism, a yuga (Sanskrit: युग, romanized: yuga, lit. 'age') is an epoch or era. There are a total of four yugas—Satya Yuga, Treta Yuga, Dvapara Yuga, and Kali Yuga—each having 1/4th less duration and dharma than the previous, with a proportion of 4:3:2:1 (Satya most, Kali least). These four yugas combined make a larger cyclic age called a Yuga Cycle or Maha Yuga.
In Brahma's calendar, we are in his 51st year — 1st month — 1st day (day-kalpa, Shveta-Varaha Kalpa) — 7th manvantara (Vaivasvata Manvantara) — 28th maha-yuga — 4th yuga (last, kali-yuga).
According to Puranic sources, Krishna's departure marks the end of Dvapara Yuga and the start of Kali Yuga, which is dated to 17/18 February 3102 BCE. Kali Yuga ends in 428,899 CE (432,000 years).