The Jewish calendar was a human dating system to which the Sixth Doctor sarcastically referred when Peri asked for the date in "human terms". According to him, the Gregorian equivalent to the "rather impressive" year 6934 in the Jewish calendar was 3174. (PROSE: Burning Heart) 1920 equated to 5681. (AUDIO: The Mouthless Dead)
It was otherwise known as the Hebrew calendar. (AUDIO: The Mouthless Dead)