Alexander

He himself however, with the flower of his army, marched on into Hyrcania. Here he saw a gulf of the open sea which appeared to be as large as the Euxine, but was sweeter than the Mediterranean. He could get no clear information about it, but conjectured that in all probability it was a stagnant overflow from the Palus Maeotis.

And yet naturalists were well aware of the truth, and many years before Alexander’s expedition they had set forth that this was the most northerly of four gulfs which stretch inland from the outer sea, and was called indifferently the Hyrcanian or Caspian Sea. Here some Barbarians unexpectedly fell in with those who were leading Alexander’s horse, Bucephalas, and captured him.

Alexander was angry beyond measure, and sent a herald threatening to put them all to the sword, together with their wives and children, if they did not send him back his horse. But when they came with the horse and also put their cities into his hands, he treated them all kindly, and gave a ransom for his horse to those who had captured him.