Brythoneg/Cymraeg has more than two millennia history: -

The Coligny Moon lunar calendar twelve months a year - six weeks a month - five days a week.

Two thousand years ago, a bronze sheet about 1 metres by 1 metre and 5 millimetres thickness was broken into small pieces, placed in an earthenware jar and buried at a site near Coligny, Ain Province, France.

It was rediscovered when unearthed in AD 1897. The bronze pieces have now been re-assembled in the manner of a jigsaw puzzle, revealing a yearly twelve-month lunar calendar, yearly cycles repeated five times. Named the Coligny Plaque, it is inscribed with words in capital letter Latin characters, not Roman names but purely Celtic core words with added terminations. Considered a most important ancient artefact, it portrays a comprehensive Moon calendar, twelve months a year, six weeks of five days a thirty-day month. Every other
month lost one day of the fourth week to maintain a fifty-nine day bi-monthly lunar cycle.

The twelve month names are Samonios, Dumannios, Rivros, Anagantios, Ogronios, Cvtios, Giamonios, Simivisonnios, Eqvos, Elembivios, Edrinios and Cantlos. The Plaque is a record of the native Gallic Celtic language at that time, half the month names are early Welsh Brythoneg and half early Irish Gaelic, demonstrating Celtic Gallic links with the Brythonic and Gaelic languages.

I translated the twelve names as the first month SUMMER, SECOND month, THIRD month, HOARD month, OGRE month, SHELTER month, WINTER month, BUDSWELL month, LAMBING month, SPRING month, BETWEEN month and lastly FULL CIRCLE month.

Archaeologists suggest the Coligny Plaque was manufactured between 200 BC and AD 50. Having regard to the known and deduced features, I consider its actual date of manufacture could be considerably earlier. Its suggested manufacture date is not really important, what far exceeds other considerations is the message offered by the Bronze Age or Iron Age artefact. A skilfully made bronze article could properly belong to the Bronze Age well before 200 BC.

The Coligny Plaque has identical Moon calendar features to the Irish Loughcrew and Knowth petroglyphs c.3500 BC, also to Stonehenge about 2300 BC. It demonstrates a fully comprehensive lunar calendar endured for three and a half millennia until Julius Caesar decreed observance of the Julian calendar throughout the Roman Empire two thousand years ago.

My translation of the Moon calendar months twelve Celto-Gallic names was facilitated by concordance between the Moon calendar and Sun calendar seasons and events. I can recount how the ancient Stonehenge Sun calendar had sixteen months, four weeks of five days each month, 365 days a year.

This record of the Celto-Gallic language two thousand years ago is a significant source of written information concerning our forebears and their language.