 Ahasuerus is given as the name of a king, the husband of Esther, in the "Book of Esther".He is said to have ruled "from India even unto Ethiopia, over an hundred and seven and twenty provinces" - that is, over the Achaemenid Empire.There is no reference to known historical events in the story; the narrative of "Esther" provides an aetiology for Purim, and the name Ahasuerus is usually understood to refer to Xerxes I, who ruled the Achaemenid Empire between 486 and 465 BCE.