Panini, the ancient grammarian (probably belonged to 5th century or sixth century BC) mentions a character called Vasudeva son of Vasudeva, and also mentions Kaurava and Arjuna which testifies to Vasudeva Krishna, Arjuna and Kauravas being contemporaries. Megasthenes (350-290 BC), a Greek ethnographer and an ambassador of Seleucus I to the court of Chandragupta Maurya mentioned about Herakles in his famous work Indica. Many scholars have suggested that the deity identified as Herakles was Krishna
Gopal Chowdhary in: The Greatest Farce of History, Partridge Publishing, 4 March 2014, p. 183.