Drimnagh of long ago was an area covered by vast forests, its rivers populated with fish and water fowl. In the forests and on the mountainside roamed wild boar, wolves and great herds of deer. Over 5000 years ago, Neolithic people formed burial mounds in the area around Drimnagh, Crumlin and Greenhills. These burial mounds were excavated in the early 20th century and some of the burial urns and objects can be seen in the national Museum in Kildare Street. After these Neolithic people, came the Bronze age settlers who settled around Drimnagh, Crumlin and Greenhills where bronze age artifacts have been found by archaeologists. After this era came the Vikings and then to the people who left the biggest mark on Drimnagh: the Norman invaders.
In 1215 the lands of Drymenagh and Tyrenure were granted to a Norman knight, Hugo de Bernivale, who arrived with Strongbow. These lands were given to him in return for his family's help in the Crusades and the invasion of Ireland. De Bernivale selected a site beside the "Crooked Glen" , the original Cruimghlinn, that gives its name to the townland of Crumlin, and there he built his castle. This "Crooked Glen" is better known today as Landsdowne Valley, through which the river Camac makes its way to the sea. The lands around Drimnagh at this time were rising and falling hills and vast forests stretching to the Dublin mountains. All through the 13th,14th and 15th century the area around the castle was sparsely populated and a document shows that only around 11 people lived in the area during the 18th century.
Drimnagh has seen its fair share of raids and attacks by the O'Toole Clans through the years and there is record of two of the Barnewall's of Drimnagh being killed in a skirmish near Crumlin. There are many undocumented raids and battles. In the 19th century, after these tumultuous times Drimnagh saw the arrival of industries like the paper mill at Landsdowne valley and other enterprises. Small Inns and lodges were built to house travellers on there way to Tallaght or further afield. Some of these are still in business today, such as the Red Cow and The Halfway House. Buildings of note in the area around the early 19th century were the Drimnagh Lodge, The Halfway House, Drimnagh Castle.
After the 19th century we see more and more expansion out towards the Drimnagh area, but it was in the 20th century were we see housing estates and industrial estates springing up around Drimnagh. For more modern historical info please visit the Drimnagh Residents Associations excellent page on its history.