It’s important to note that the Aryan invasion theory is entirely a nineteenth century European creation. It finds no support in ancient Indian records, which recognizes no homeland other than India. Also, the theory was formulated when there was no archaeology or scientific methods to assist nineteenth century European scholars who also for the most part lacked scientific education. Most of them believed in the Biblical theory of creation according to which the world and all the living things were created at 9:00 am on October 23rd 4004 BC. For several centuries it was a serious offence to question this Christian dogma. Firm belief in this dogma led early Indologist to manipulate Indian history and chronology to fit everything within the framework of this Biblical superstition.
History books do not mention this Biblical background – most authors probably are even unaware of it – but unwittingly they still carry the legacy of this Christian Fundamentalist doctrine. It was later presented in the linguistic terms, and the chronology of ancient India and the date of the Rigveda found in history books were made to rest on these Biblical beliefs: Creation in 4004 BC and the Biblical floods in 2448 BC. Nor is this the only contributor to the Aryan invasion theory, European and British colonial interest too played their role.