It’s not Ambani nor TATA who is all times richest Indian but it is Hyderabad’s last Nizam who is termed as the richest Indian of all time..
Osman Ali Khan was the last Nizam of Hyderabad.
According to a new inflation-adjusted list of the world’s richest people of all time, the Nizam, who ruled Hyderabad between 1886-1967, was ranked sixth with USD 236 billion.
Osman Ali Khan died in 1967 at age of 80. Mansa Musa I of Mali – the obscure 14th century African king – was named the richest person in all history, British newspaper ‘The Independent’. [source]
According to this data the now richest person in the world Carlos Slim would have been ranked at 22.
The list uses the annual 2199.6 per cent rate of inflation to adjust historic fortunes – a formula that means USD 100 million in 1913 would be equal to USD 2.299.63 billion today.
Here is one more graphical presentation from the Indian History – Historic Indian GDP