200 BC to 400 AD: The Hopewell culture of this time could be called the flowering of the Adena people of the Mississippi drainage area of North America.
133 BC: Some Celts probably came to Ireland after the Roman invasion of Spain, but had already appeared on the island before 1400 BC.
80 BC: Arrival of the Gauls and of Carthaginians traders to Ireland had begun.
66 AD: Notable comets around the Earth striking earth and sea.
c.100 AD to 700 AD: A Runic script called Elder Ruth was used by Germanic-speaking peoples.
200 AD: Good documentation of writing used in Ireland by this time.
~ Beginnings of "High Kingship" at Tara, Co. Meath, Ireland.
300 AD Hopewell Tradition reaches greatest extension in North America. Influence was probably felt from what is now Canada to what is now Cuba. Also far east and west.
~ by this time Romans were calling some peoples in Ireland Scoti.
350 AD: Christianity reaches most of Ireland.
377 AD to 405 AD Niall of the Nine Hostages is High King to many in Ireland.
400 AD: Hopewell period ends in N. A. and the \woodland period began there.
432 AD: Traditional date of arrival of St. Patrick in Ireland. Arrival of St. Patrick to help convert pegan Gaelic kings to Christianity.
461 AD: St. Patrick dies, after having Achieved his dream of introducing both Roman civilization and the Christian church to Ireland.
550 AD: onward Irish monks re-Christianized Europe.