עזרא ו:ב פירוש: רש״י

And there was found in a pouch And a text of one scroll was found there in an אַחְמְתָא. So did the interpreters interpret, that it is a receptacle made for letters, written sheets and books, and they established it from the root of (Gen. 21:14): “a skin of water (וְחֵמַת מַיִם),” and the “aleph” in the word is not a radical, like the rest of the Aramaic language.

in the citadel in that citadel that was in the province of Media.

and so was written and so was written therein its memorandum.