There seems to be some confusion here between the Ages, which are astronomical and last approximately 2,000 years and the Yugas, which, as you mention, are MUCH longer.
A Maha Yuga is 4,320,000 years.
Sat Yuga (Golden Age - Age of Truth) is 1,728,000 years.
Treta Yuga (Silver Age - Age of Faith) is 1,296,000 years.
Duapar Yuga (Bronze Age - Age of Doubt) is 864,000 years.
Kali Yuga (Iron Age - Age of Darkness) is 432,000 years.
Together, the four Ages comprise one Maha Yug (Great Age) of 4,320,000 years. The ratio of Yuga duration is thus 4:3:2:1 totaling the 4,320,000 years of Maha Yuga. Two thousand Maha Yugas (8,640,000,000 years) are said to equal merely one day and one night in the life of Brahm.
Dawn of the present phase of the Kali Yuga is 3606 B.C.
Middle is 582 B.C.
Twilight is A.D. 1939
End is A.D. 2442
The Astrological Ages
Each 'Great Age' lasts approximately 2,000 years, roughly speaking, and they move backwards through the constellations: therefore, we are now moving out of the Piscean age and into the Aquarian age.
Before Pisces there were the Arien, Taurean, Geminian, Cancerian, Leonian ages, and so on.
Age of Leo (Sun) 10,000 BC - Atlantis - early Egypt (Ra worship)
Age of Cancer (Moon) 8,000 BC - destruction of Atlantis by water
Age of Gemini (mind) 6,000 BC - Babylonia Assyria (cuniform writing)
Age of Taurus (bull) 4,000 BC - Egypt (worship of bull portrayed with sun between horns)
Age of Aries (Mars) 2,000 BC - Romans (war, exploration, conquest)
Age of Pisces (Neptune) 0 BC - Buddha, Zoroaster, Confucious, Lao-tse, Jesus
Age of Aquarius (Uranus) 2,000 AD - Universal consciousness, Khalsa
