Is this name India derived from Indus as we have been taught from childhood or the name actually derived from Indra- The God of the Purus(Vedic Aryans). Indra(just replace 'r' with 'i') -> India.
we don't know what type of Sanskrit dialect other tribes like the Iksvakus, Yadus, Turvashus, etc used to spoke. Iranians(Anu descendants) used to pronounce some words with replacement of 'S' with 'H' like Sindhu->Hindu, Sarayu->Harayu, Sarasvati->Harahvati, Soma->Homa, etc,
possibly other tribes to pronounce Indra/Indara as just Inda/Indya. Greeks giving this name India derived from Indus is nothing but propaganda to promote fake greek supremacy. Greek->Alina(Helina/Helena/Hellenes)->Anu tribe-anti Puru, anti Vedic tried to omit Indra's identity. 
why would the Greeks be calling this country after the name of a river. As an hypothetical example, the Greeks never call Egypt as niledia/nildania/nildus after Egyptian river Nile. This word India has been in use in Greek since Herodus (400 BC).
Even in Indian tradition this divine land was called by various names like Jambudvīpa , Āryāvarta , BharatVarsha, Nabhivarsha, but never it has been named after any river.
Even if we consider that it was named after a river then why Indus (Sindhu). Indus was not a major river at least not until the time the Vedic Aryans moved to west from east.
Ganga, Yamuna, Sarasvati was some of the primary major rivers in the Vedas in the early as well as in the late part. Sindhu get status in the middle and late part of the RigVeda.
Also another interesting point, all the rivers Ganga, Yamuna, Sarasvati was and is still being worshiped as Goddess in Hindu culture but not Indus. Never heard of any Sindhu Mata.
The present narrative that Persian used to pronounce Sindhu as Hindu which the Greek used to pronounce as Indu/Indos from which ultimately the word India derived is not wholly wrong but not appropriate. Both the word India and Indus perhaps actually derived from Indra.
