Hindus think that there are four very long ages, or epochs, called yugas, which continuously rotate. Time is in a total cycle of 4,320,000 years, made up of: the yuga of gold (1,728,000 years); the yuga of silver (1,296,000 years); the yuga of copper (864,000 years); and the yuga of iron (432,000 years). Each age gets shorter and more corrupt. We are living in the age of iron. So, given that human existence in the world is 5000 years into the age of iron, this leaves 427,000 years remaining until the tenth avatar of Vishnu will appear as Kalki, riding a white horse. He will kill off the remaining evil and evil-doers in the world and bring about the birth of another golden age, and so a new cycle of time will start.