This reflection about names of places and countries started from the book "Empires of the Indus" written by Alice Albinia.
Indus is the mighty river that starts from high mountains in Kashmir and goes to end in the Indian ocean through a wide delta in Sindh region of Pakistan. All the other important rivers on the western parts of India (Satluj, Ravi & Beas), Pakistan (Jhelum & Chenab) and eastern part of Afghanistan (Kabul), end in Indus. It is this river that gave India its name, though today most of it belongs to Pakistan.
Albinia writes that when India was divided, and Pakistan chose its new name, Jinah was expecting India to take the official name of Bharat and was aghast when it decided to keep India as its name, the name of the undivided country. It meant that India could claim the heritage and history of the past associated with the name "India", while Pakistan had to invent a new history for itself.
However, this reflection about Indus and India took me into another direction of thoughts. The Indian name for Indus river is Sindhu.
Rajesh Kochhar in his book "The Vedic People - their history and geography", makes an interesting point about development of languages in western part of the Indian subcontinent. His story starts with persons from central Asia. They moved into Afghanistan and then some of them migrated towards Sindhu river (Rigvedic people, as they wrote Rigveda) and others went towards Persia/Iran (Avestan people, as they wrote their sacred book Avesta). Later, as iron became available and thick jungles in the gangetic plains could be cut, the Rigvedic people migrated deeper into India.
Kochhar says that Avestans, used "H" more commonly in their language while Rigvedic people used more "S" in their language. Thus, Rigvedic group had names of many places and rivers starting with "S", including Sindhu river, while Avestan group had the same names starting with "H". So that for the Avestan group, Sindhu became Hindu.
Among other things, Kochhar proposes that Rigveda is mainly about three thousand years BC, when these persons were living in what is today called Afghanistan. To support this theory he explains the lack of references to Ganga river (Ganges) in Rigveda. Thus, he says that Sarayu river of Rigveda is not the present Sarayu in Uttar Pradesh, but is actually Haroyu (present name Hari Rud) of Afghanistan; in the same way, he arguments that Rigvedic Sarasawati river was actually the mighty Afghani river, Harahvaiti.
That is how, persons living on banks of Sindhu river were called Hindu and their religion became Hinduism. Come to think of it, Rigveda also does not mention any religion called "Hindu".
And, where did the word Indus came from? I guess, it came from Latin, the language of Roman empire and the lingua franca of the classical Europe, where "H" is silent and rarely used. For example, in Italian, Hinduism is called "Induismo" and Himalaya becomes "Imalaia". Therefore, the name of Indus river and country's name, India, both probably come from Latin.
All these reflections about names of places and country, worry me a little.
Thinking of all the campaigns for reclaiming our roots through name changes (Mumbai, Bengalaru, Chennai, etc.), perhaps one day there will be a campaign to change India's name to Sindhia and Hindus can call themselves Sindhus, and Hindi can become Sindhi?
That obviously raises another question - how are Sindhis going to call themselves?