Original sentence: At around 1500 BC, the influx of Aryan tribes from the northwest of India and their merger with the earlier inhabitants created the classical Vedic culture.However, recent research holds that there could have been a more peaceful transition.The earlier, more widely known theory was that this influx was through an invasion(Aryan invasion theory)
Edited sentence: According to the controversial but widely accepted Aryan invasion theory, Aryan tribes from the northwest of India invaded about 1500 BC, and their merger with the earlier inhabitants created the classical Vedic culture