What is "tishrei"

Tishrei or Tishri ( or ; ; from Akkadian tašrītu "Beginning", from šurrû "To begin") is the first month of the civil year (which starts on 1 Tishrei) and the seventh month of the ecclesiastical year (which starts on 1 Nisan) in the Hebrew calendar. The name of the month is Babylonian. It is an autumn month of 30 days. Tishrei usually occurs in September–October on the Gregorian calendar.

In the Hebrew Bible, before the Babylonian Exile, the month is called Ethanim ( - ).

Edwin R. Thiele has concluded, in The Mysterious Numbers of the Hebrew Kings, that the ancient Kingdom of Judah counted years using the civil year starting in Tishrei, while the Kingdom of Israel counted years using the ecclesiastical new year starting in Nisan. Tishrei is the month used for the counting of the epoch year - i.e., the count of the year is incremented on 1 Tishrei.