The death toll of the conflict was huge. William Petty, a Cromwellian who conducted the first scientific land and demographic survey of Ireland in the 1650s , concluded that at least 400,000 people and maybe as many as 620,000 had died in Ireland between 1641 and 1653. The true figure may be lower, but the lowest suggested is about 200,000. At the time, the population of Ireland was only around 1.5 million inhabitants. It is estimated that about two thirds of the deaths were civilian. The Irish defeat led to the mass confiscation of Catholic owned land and the English Protestant domination of Ireland for over two centuries. The wars, especially the Cromwellian conquest, were long remembered in Irish culture. Gaelic Poetry of the post-war era laments lack of unity among Irish Catholics in the Confederation and their constant infighting, which was blamed for their failure to resist Cromwell. Other common themes include the mourning of the old Irish Catholic landed classes, which were destroyed in the wars, and the cruelty of the Parliamentarian forces. See Also Irish Poetry
Question: How many years was the time span that at least 400,000 people and maybe as many as 620,000 had died in Ireland?
Answer: 12