According to historians, the origin of Hinduism dates back to 5,000 or more years. The word "Hindu" is derived from the name of River Indus, which flows through northern India. In ancient times the river was called the 'Sindhu', but the Persians who migrated to India called the river 'Hindu', the land 'Hindustan' and its inhabitants 'Hindus'. Thus the religion followed by the Hindus came to be known as 'Hinduism'.
It was earlier believed that the basic tenets of Hinduism were brought to India by the Aryans who invaded the Indus Valley Civilization and settled along the banks of the Indus river about 2000 BC. However, this theory has now been proved to be a flawed one and is considered nothing more than a myth.
According to scholars, the evolution of Hinduism may be divided into three periods: the ancient (6500 BCE-1000 AD), the medieval (1000-1800 AD), and the modern (1800 AD to present). Hinduism is commonly thought to be the oldest religion in the history of human civilization.