Tenshō era

The Tenshō era is a named period of imperial dating that places 1576 in its fourth year, the Year of the Rat. Its explanation gives the calendar more than a numbering function: era names could mark a new imperial period, while the animal-year sequence located individual years within a recurring cycle.

Naming the Era

An era began or ended at the ruling Emperor’s discretion. A catastrophe or a godsend might prompt such a change, and scholars were directed to choose an auspicious name from ancient Chinese books. Tenshō means Heaven Righteousness. The system therefore joined political authority to an act of interpretation: an emperor determined when a period turned, while scholars supplied a name meant to carry favorable meaning.

Numbering the Years

Each year carried both a number within its era and an animal designation from a twelve-part sequence: Hare, Dragon, Snake, Horse, Goat, Monkey, Cock, Dog, Boar, Rat, Ox, and Tiger. The account explains the date 1576 through these linked measures: the first year of Tenshō fell in the Year of the Cock, making 1576 the fourth year and the Year of the Rat. Era year and animal year thus work together to specify a date.

Historical Scale

The calendar’s account of time places individual years beside events of immense human consequence. The year before the fourth year of Tenshō was the year of a great tidal wave in which two hundred thousand people died. The passage does not say that this disaster caused an era change; instead, it establishes catastrophe as one kind of occurrence that could bring an era to an end or begin another. In the surrounding conversation, the date of arrival also gives Toranaga a point from which to measure the twenty-four years that have since passed.