4000BC
Stone age people begin small scale clearance of forests of oak, birch and hazel.

2000BC
Bronze Age settlers erect cairns and standing stones.

500BC
Ordovician Celts arrive from Europe.

87BC-400AD
Roman occupation, temporary military camp is established at Esgair Perfedd.

500AD
Celtic monks start to farm the hills on a permanent basis.

600AD
Monastic settlement at Dôl y Mynach (Monks meadow) was established.

1171
Rhayader Castle was built by the Welsh Prince, Rhys ap Gruffudd.

1184
The lands of Cwmdeuddwr parish, including the Elan and Claerwen area, were given to the Cistercian Abbey of Strata Florida by Rhys ap Gruffudd.

1195
Rhys ap Gruffudd defeated by Mortimer at Painscastle.

1231
Rhayader Castle destroyed by Llywelyn the Great.

1300s
Extensive forest clearance of Elan ordered by Edward I, due to the trees sheltering thieves. Increases wealth of this once major wool-producing area.

1536
Act of Union brings Wales under English law. All the monastic lands become the property of the Crown of Henry VIII.

1796-1877
Cwm Elan metal mines productive.

1798
William Lisle Bowles (poet) visits Cwm Elan and publishes the poem Coombe-Ellen.

1809
Thomas Grove Jnr. (cousin to Shelley) becomes Master of the Cwm Elan Estate.

1811
The poet Percy Bysshe Shelley visits Cwm Elan between June and August.

1812
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.

1843-1844
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.

Late 1800s
Poach-ins (organised poaching) occur in defiance of attempts to regulate the salmon fisheries.

1883-1899
Nant y Garw lead mine in the Rhiwnant Valley productive.

1892
Act of Parliament passed allowing the purchase of the watershed land, for the building of the dams.

1893
Work begins on the building of the Elan Valley dams.

1904
Elan Valley dams completed and opened by King Edward VII and Queen Alexandra.

1914-1918
1939-1945
World Wars I and II. Dams are specially guarded against attack.

1946
Work begins on Claerwen Dam.

1952
Claerwen Dam is opened by Queen Elizabeth II as one of her first duties as monarch.

1965
The first Site of Special Scientific Interest is designated on the Estate.

1974
The individual water companies are designated and Dŵr Cymru Welsh Water is given responsibility for the Elan Estate, dams and reservoirs.

1985
Elan Valley Visitor Centre opens.

1989
Elan is included in the Cambrian Mountains Environmentally Sensitive Area.
The Welsh Water Elan Trust is established after privatisation of the Water Companies to protect the wildlife of the Estate and encourage public access and understanding.

1995
Elenydd-Mallaen is designated a Special Protection Area under the European Wild Birds Directive.

1997
New Visitor Centre extension opens.

2004
Elan dams celebrate their centenary, with a series of special events.