Hindu - Etymology

Etymology

The Brihaspati Agama (dated?)says:

हिमालयं समारभ्य यावदिंदुसरोवरम् ।
तं देवनिर्मितं देशं हिंदुस्थानं प्रचक्ष्यते ।।
"The land created by the gods which stretched from the Himalayas to the Indu (i.e. Southern) ocean is called Hindusthan, with the हिंदु (Hindu) mentioned in word हिंदुस्थानं (Hindusthan)."

The usage of the word Hindu was popularized for Arabs and further west by the Arabic term al-Hind referring to the land of the people who live across river Indus and the Persian term Hindū referring to all Indians. By the 13th century, Hindustān emerged as a popular alternative name of India, meaning the "land of Hindus".

The term 'Hindu' occurs sporadically in some 16th-18th century Bengali Gaudiya Vaishnava texts, including Chaitanya Charitamrita and Chaitanya Bhagavata, usually to contrast Hindus with Yavanas or Mlecchas. It appears in South Indian and Kashmiri texts from at least 1323 CE, and increasingly so during British rule. It was only towards the end of the 18th century that the European merchants and colonists referred collectively to the followers of Indian religions as Hindus. Eventually, it came to define a precisely religious identity that includes any person of Indian origin who neither practiced Abrahamic religions nor non-Vedic Indian religions, such as Jainism, Sikhism or Buddhism, thereby encompassing a wide range of religious beliefs and practices related to Sanātana Dharma.

The term Hinduism was formed around 1830 to denote the culture and religion of Indians in contrast to other foreign religions. It was soon appropriated by the Hindus in India themselves as they tried to establish a national, social and cultural identity.