Kurukshetra is ithasa.
Greek sources too.
He is referred as "Herkalece" in megesthans's Indica (Greeks gave hellenic names to most of foreign heroes) . Though that source is said to be based on hearsay.
The thing is that most of facts stated in mythology are true though highly exaggerated. It was the way history was written in older time.In this time, a war between 7000 greeks and 100-200,000 Persians become a war of 300 Spartans and 2 million Persians in Herodotus's account of war. This does not mean that Battle of Thermopylae did not take place.
Similarly, sites of Trojan war have been recently discovered in Asia minor.
Even today most of mythical novels are based on real life events. Game of thrones is based on war of roses that took place in England with other events from British history added to it (Red wedding is based on Black dinner and Glencoe massacre).
The parallels are even more stark in lord of the rings , especially if you read simmilarion with LOTR and the hobbit. It describe christian muslim war for most of the part. Here Allah is melkor, mohommad is sauron,Orcs are muslims, minas tirith is constantinople,Siege of rohan describe second siege of vienna which was broken by cavalry charge of Jan spralosky III. Even geography of Mordor is same as that of Turkey.
And if you read simmilarion, you would find that Orcs initially were elves who were way from path of light by melkor ( an allegory of Islam converting Christians.
