It is based on both, language and biology (which includes genetics).

Aryans had dominated different forms of technology for several years before recorded history.

This book is mind blowing, it presents an interesting thesis:

http://www.amazon.co.uk/dp/1496168771

“Chronicles from pre-Celtic Europe” is a factual account of European and Asian pre-history as described in an ancient manuscript discovered in the Netherlands in 1867. The old chronicles tell of an advanced European civilisation that existed more than 4000 years ago; a civilisation unknown to or denied by historians to this day. The manuscript is compared to numerous authors from antiquity and tested against modern sciences such as archaeology, paleoclimatology, genetics, linguistics and many more. Undeniable evidence proves that this highly controversial but captivating document, Europe’s “Rosetta Stone”, is true in every respect. It shows that West European Civilisation pre-dates Greek and Roman societies by millennia and that many milestones which were in the past attributed to the Greeks, Romans, Phoenicians, Egyptians and others should, in fact, be accredited to North-Western Europe. The old manuscript which became known as “The Oera Linda Book” is still rejected by certain Dutch academics as a “Hoax” or a “Deception Conspiracy” by unidentified pranksters and without a clear motive; their opinions and theories based on no more than intuition. The Oera Linda manuscript relates the memoirs and eye witness accounts of men and women from Western Europe who suffered the biggest catastrophe in the recorded history of man; the event that killed millions and came down to us as “Noah’s Flood”. The pioneers from Europe’s Western seaboard founded the ancient civilisations from Greece to Persia. They introduced the world to carbonised steel, chariot warfare and cavalry charges. They gave man the “Greek” alphabet, “Indo-Arabian” numerals, democracy, free enterprise, monotheism, linen, paper and so much more. It is time to set the record straight.

There is not a definitive answer for where exactly Aryans come from. However, today we know that Aryans are totally different from other races, thus it is quite likely Aryans never came from Negroes.