Hadean
The Hadean () is a geologic eon of the Earth pre-dating the Archean. It began with the formation of the Earth about 4.6 billion years ago and ended, as defined by the ICS, 4 billion years ago. , the ICS describes its status as ""informal"". Geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term, the "Priscoan period", from "priscus", the Latin word for "ancient". Other, older texts simply refer to the eon as the Pre-Archean.
Historical Vedic religion
The Vedic period is held to have ended around 500 BCE. The period between 800 BCE and 200 BCE is the formative period for later Hinduism, Jainism and Buddhism. According to Michaels, the period between 500 BCE and 200 BCE is a time of "ascetic reformism". According to Michaels, the period between 200 BCE and 1100 CE is the time of "classical Hinduism", since there is "a turning point between the Vedic religion and Hindu religions". Muesse discerns a longer period of change, namely between 800 BCE and 200 BCE, which he calls the "Classical Period", when "traditional religious practices and beliefs were reassessed. The brahmins and the rituals they performed no longer enjoyed the same prestige they had in the Vedic period".