Stone age people begin small scale clearance of forests of oak, birch and hazel.
Bronze Age settlers erect cairns and standing stones.
Ordovician Celts arrive from Europe.
Roman occupation, temporary military camp is established at Esgair Perfedd.
Celtic monks start to farm the hills on a permanent basis.
Monastic settlement at Dôl y Mynach (Monks meadow) was established.
Rhayader Castle was built by the Welsh Prince, Rhys ap Gruffudd.
The lands of Cwmdeuddwr parish, including the Elan and Claerwen area, were given to the Cistercian Abbey of Strata Florida by Rhys ap Gruffudd.
Rhys ap Gruffudd defeated by Mortimer at Painscastle.
Rhayader Castle destroyed by Llywelyn the Great.
Extensive forest clearance of Elan ordered by Edward I, due to the trees sheltering thieves.
Act of Union brings Wales under English law. All the monastic lands become the property of the Crown of Henry VIII.
Cwm Elan metal mines productive.
William Lisle Bowles (poet) visits Cwm Elan and publishes the poem Coombe-Ellen.
Thomas Grove Jnr. (cousin to Shelley) becomes Master of the Cwm Elan Estate.
The poet Percy Bysshe Shelley visits Cwm Elan between June and August.
In April Shelley returns with his wife Harriet to settle in the Elan Valley, this time residing at Nantgwyllt. Financial and political circumstances force them out of their home by June.
General economic depression and long standing discontent with the tolls charged by the Turnpike Trusts lead to the Rebecca Riots, so named because the attackers disguise themselves by blackening their faces and wearing womens clothes.
Poach-ins (organised poaching) occur in defiance of attempts to regulate the salmon fisheries.
Nant y Garw lead mine in the Rhiwnant Valley productive.
Act of Parliament passed allowing the purchase of the watershed land, for the building of the dams.
Work begins on the building of the Elan Valley dams.
Elan Valley dams completed and opened by King Edward VII and Queen Alexandra.
World Wars I and II. Dams are specially guarded against attack.
Work begins on Claerwen Dam.
Claerwen Dam is opened by Queen Elizabeth II as one of her first duties as monarch.
The first Site of Special Scientific Interest is designated on the Estate.
The individual water companies are designated and Dŵr Cymru Welsh Water is given responsibility for the Elan Estate, dams and reservoirs.
Elan Valley Visitor Centre opens.
Elan is included in the Cambrian Mountains Environmentally Sensitive Area.
The Elan Valley Trust is established after privatisation of the water companies to protect the wildlife of the Estate and encourage public access and understanding.
Elenydd-Mallaen is designated a Special Protection Area under the European Wild Birds Directive.
New Visitor Centre extension opens.
Claerwen Dam celebrates its half-centenary with the dam being opened for visitors to look inside.
Elan Valley Dams celebrate their centenary, with a series of special events.