Spoken to few linguistics but have been unable to establish hindu came from hind or hind came from hindu
'Hind' came from 'Hindu'.
Let me explain.
The etymology is from the name of the river that flows through contemporary Pakistan, that is marked on the maps as Indus.
It was named 'Sindhu' by people living on the banks, a name that has been traced back to 'many waters', or 'vast waters', and that comes originally from an Indo-Iranian word. I read this nearly 30 years ago, and cannot give you a citation.
That name was transposed to 'Hindu' by the people of the Iranian plateau and its neighbouring hill country, that we now know as Afghanistan, who had an accent wherein many Indo-Aryan words were converted from sibilant to aspirate form; 's' became 'h'. So Saraswati became, in Afghanistan, Harahoti or Haraothi.
The Greeks who lived on the western fringe of the Achaemenid Empire, after Anatolia was conquered, and their Anatolian habitations came under Achaemenid rule, were inveterate travellers and merchants and soon found their way to these eastern parts, taking advantage of the Pax Persica that prevailed. They, too, had an accent; it tended to lose the aspirate altogether. The 'h' sound was lost. 'Hindu' thus became 'Indu', and a Greek termination was added to make it 'Indos'. Ironically, that name is retained today but there are many well-meaning and not too deeply knowledgeable gentlemen who object violently to the name India, the foreign name for our country since at least the time of Megasthenes, a Seleukid ambassador to the Mauryas at their capital in Pataliputra (currently in the Indian state of Bihar).
The word Hind was coined a few centuries later, by Arabs and Persians - it is not clear who said it first - as a name for the black men of the region of the Indus and parts east of that. 'Hind' and 'Hindu' meant 'black'; it later came to mean thief or generally socially avoidable character. It was later broadened to mean the country of the Indus valley and to the east. That is how we got 'Hind' and 'Hindu'.