Original sentence: Archaeologically, this period corresponds with the  Indus Valley Civilization (IVC), Cemetery H cultures of the Punjab and the  Ochre Coloured Pottery culture (OCP) further east.It is undisputed that there is a strong component of cultural continuity of the indigenous IVC.Its creation must have taken place over several centuries, and apart from the youngest books (1 and 10), it must have been essentially complete by 3000 BCE.Strong traces of a common Indo-Iranian religion remain visible, especially in the Soma cult and  the fire worship also preserved in Zoroastrianism, suggesting that Proto-Indo-Iranian broke off in the Indian subcontinent as per the Out of India theory.ru:Ведическая цивилизация
Edited sentence: Its creation must have taken place over several centuries, and apart from the youngest books (1 and 10), it must have been essentially complete by the early first century.Strong traces of a common Indo-Iranian religion remain visible, especially in the Soma cult and  the fire worship also preserved in Zoroastrianism