There are four yugas widely accepted in Hinduism. They are :
1. Satya yug
2. Treta yug (Ramayana)
3. Dwapara yug(Mahabharata)
4. Kal yug(Present)
In Satya yug, the fight was between two worlds (Devalok & Asuralok). Asuralok being the evil, was a different WORLD.