Wikipedia
Idanthyrsus is the name of two Scythian kings:
1.The first one led Scythians, under whom, according to Strabo, they overran Asia, and advanced as far as Egypt. This was perhaps the incursion mentioned by Herodotus, who tells us that they held Asia for 28 years, and were ultimately driven out by Cyaxares, 607 BC. According to Herodotus, however, the king, who led the expedition of which he gives an account, was Madyas; and Madyas is mentioned by Strabo (i. p. 61) as king of the Cimmerians. An incursion of the Scythians to the borders of Egypt in very early times is recorded by Justin, but in an obscure and unsatisfactory way.
2. Another king of the Scythians, probably a descendant of the above. He was a son of Saulius, the brother and slayer of Anacharsis. When Darius I of Persia invaded Scythia, about 513 BC, and the Scythians retreated before him, he sent a message to Idanthyrsus, calling upon him either to fight or submit. The Scythian king answered that, in fleeing before the Persians, he was not urged by fear, but was merely living the wandering/ nomadic life to which he was accustomed, that there was no reason why he should fight the Persians, as he had neither cities for them to take nor lands.
He, however did reply, "But if all you want is to come to fight, we have the graves of our fathers. Come on, find these and try to destroy them: you shall know then whether we will fight you."
In his Histories, Herodotus writes the following about the dialogue between the Persian king and Idanthyrsus (2015 publication, Knopf Doubleday Publishing Group);
To which the Scythian king replied;