The historical and etymological genesis of the word `Hindu' is an ongoing controversy. Indologists differ in their opinion regarding the origin of the word ‘Hindu.’ The term ‘hindu’ is not a Sanskrit word and scholars have not acknowledged the use of the word in Vedic literature.
But there is a generally accepted scholarly view regarding the origin. The word ‘Hindu’ is derived from the River Sindhu otherwise known as
Indus. According to Monier Williams, ‘that part of the great Aryan race which immigrated from Central Asia, through the mountain passes into India, settled first in the districts near the River Sindhu (now called the Indus). The Persian pronounced this word Hindu and named their Aryan brother Hindus. The Greeks, who probably gained their first ideas of India Persians, dropped the hard aspirate, and called the Hindus `Indoi'.
Dr Radhakrishnan also echoes similar views. He writes in the ‘The Hindu Way of Life’ ‘the Hindu civilization is so called, since it original founders or earliest followers occupied the territory drained by the Sindhu (the
Indus) river system corresponding to the North-West Frontier Province and the Punjab. This is recorded in the Rig Veda, the oldest of the Vedas, the Hindu scriptures which give their name to this period of the Indian history. The people on the Indian side of the Sindhu were called Hindu by the Persian and the later western invaders. That is the genesis of the word `Hindu'.