According to Hindu scriptures, Kali Yuga, the last of the four stages that the world goes through as part of the cycle of yugas, began. 4th millennium BC: The 4th millennium BC spanned the years 4000 BC to 3001 BC. It marked a critical turning point in human history, characterized by the transition from late Neolithic agricultural societies into urban, state-level civilizations. February 18, 3102 BC. Wiki link