Everyone is subjected to achieving heroic virtues, natural competitive dominance but in a class system, their life is mostly governed by penance and charity. The divine presence fades away as people administer kingly and pleasure seeking traits whilst forgetting their divinity. People are punished with ailments, diseases and varius types of desires. The realization of reality (material) gives them a need for performing penance.
Dvapara yuga lasts 864,000 years
Its the third of the 4 cycles of life.