One system of dating used by the Celtic peoples refers to the Great Council of Druids which was convened in response to the growing threat of Roman power. The decisions reached by the Council were
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Henge Koth, traditionally considered the meeting place of the Great Council

instrumental in eventually repelling the Roman threat, which is why this event is viewed as so significant by the Celtic peoples.

The year in which the Council was convened is denoted by 1 O.K. where O.K. is taken to stand either for Oes Keltek (Celtic Age) or Oes Konsel (Council Age).

1 O.K. corresponds to 99 B.C.E. (see below), OTL.

Years prior to the Council are denoted by K.K., Kyns Keltek (Before Celtic) or Kyns Konsel (Before Council).

There is no year 0. The year 1 K.K. was followed by the year 1 O.K..

Conversion Between Calendars

To convert K.K. dates to B.C.E. (Before Christian Era, aka B.C.)(OTL)

Add 99 to the K.K. date to obtain the

e.g. 21 K.K. = 120 B.C.E.

To convert O.K. dates to B.C.E (OTL)

Years 1 O.K. to 99 O.K. correspond to years 99 B.C.E to 1 B.C.E. (OTL)

Subtract the K.K. date from 100 to obtain the B.C.E. date

e.g. 9 O.K. = 91 B.C.E.

To convert O.K. dates to C.E. (Christian Era, aka A.D.) (OTL)

Years 100 O.K. onwards correspond to years 1 C.E. onwards (OTL)

Subtract 101 from the O.K. date to obtain the C.E. date

e.g. 110 O.K. corresponds to 9 C.E.

2111 O.K. corresponds to 2010 C.E.

To convert from B.C.E./C.E. dates to K.K./O.K. dates

Reverse the calculations above.