A well-known feature of the Hebrew of the Bar-Kosiba letters, dated to the third decade of the second century CE, is a reduced form of the earlier direct object marker את, which appears in the letters in written form as ת t-, attached the following word, i.e., תשמים `the heavens`. The form underlying the written representation has been discussed by scholars. It has been compared by Kutscher to a similar form of the direct object marker in Modern Hebrew, and Gzella, who reconstructs the form as /ta-/, has suggested Aramaic influence as a factor in the development of Bar-Kosiba Hebrew t-, in particular the Aramaic preposition /la-/. Gzella has pointed out that the reduced form appears not only before nouns possessing a definite article, but even before the interrogative element מי my-, which cannot take the definite article in Hebrew. This fact indicates a historical process deeper than mere phonological reduction underlying the development of t-.
In my lecture I present my own suggestion for the development of t- of the Bar-Kosiba letters, connecting it morphophonemic and morphosyntactic developments in other varieties of Hebrew from the first half of the first millennium CE.