On 26 January 1972, Idukki District was formed by carving out taluks such as Devikulam, Udumbanchola and Peerumade from Kottayam District and Thodupuzha from Ernakulam District. On 14 February 1972, the district name Idukki was derived from the word ‘Idukku’ in Malayalam, which means a gorge (Valley). The area North Pamba Valley and around Sabarimala Sannidhanam in Malappara Village of Peerumade Taluk were transferred to Pathanamthitta District on 29 October 1982. At present, this district consists of five taluks namely Devikulam, Udumbanchola, Thodupuzha, Peerumade and Idukki.
The pre-history (Palaeolithic period) of this district is hidden or no clear evidence found. Many graves, dolmens, menhirs, uru buriah, the vaults are found high which are dated back to the Megalithic period. The State Archaeology Department discovered many characteristics of prehistoric civilization in Marayoor, Anchunad Valley of Devikulam Taluk, Thengakkal near Vandiperiyar, Bison Valley and Thondermalai. In early days, these places indicated the cultural and developed civilization of inhabitants. In ancient times, the traders in this district gave importance to selling spices such as pepper, cardamom, etc, which are grown in abundance in the state.
Kuzhumur, the present Kumily in Peerumade Taluk of this district, was the capital of early Chera Empire which was believed by historians. Under the rule of Kulasekharas Empire many places like Nanthuzainad inclusive of Devikulam, Udumbanchola and Peerumade Taluks, Vempolinad and Manjunad of Kottayam District and Kuzhumelainad inclusive of Thodupuzha Taluk are part of its empire. In 1100 AD, many places in Kerala became the capital of Vadakkumkur Rajas such as Vempolinad were split up into Vadakkumkur, Thekkumkur, Karikkode in Thodupuzha Taluk. For a long period, he was subordinate to the Perumpadappu Swaroopam. In those days, the powerful Kingdom Thekkumkur was the most powerful Kingdom and occasionally there were quarrels between Cochin and Vadakkumkur Kingdoms.
Travancore State was divided into four Revenue Divisions in the early days. Even though there was not much revenue from Cardamom Hill, it was treated as a separate division for magisterial and general planning. In 1909, a fifth division in the state viz Devikulam was carved out taking regions of adjoining taluks of Kottayam division. Later, this revenue division was considered a good collection. For a few decades, there were no changes in jurisdiction till September 1956. During 1931-41, this division was annexed with the Northern Division. Udumbanchola taluk was newly constituted by taking two villages from Devikulam taluk and one village from Peerumade taluk on 1 October 1956.
The enormous growth of pepper in this district attracted the Dutch East India Company. The company had a treaty signed on 16 June 1664 to have trade contracts on spices, cinnamon, opium, etc with Thekkumkur Rajas. One of the famous Pandya King, Manavikramakulasekhara Perumal along with his family members immigrated to Kerala and settled in Vadakkumkur as refugees. The Pandya King bought a portion of land located in the West of the Western Ghats known as Poonjar from Thekkumkur Rajas. Poonjar Raja acquired the few areas from Peerumade to Devikulam which are part of Idukki District in the 15th Century. Thekkumkur and Vadakkumkur, the Poonjar Principality was also annexed to Travancore in 1749-50 then the history was associated with Travancore. Compared to other parts of the state, the people in this district took less participation in freedom fights.
The history of the present population in this district is very recent and exploitation of labour and labour struggles. This district has brave weather, wild animals and epidemics. The district began the ministry of Sri. T.K. Narayana Pillai started a food campaign in the state which was very helpful for the present population. This district started from Tamil Nadu in the first two decades of the present century. Maharaja Sree Moolam Thirunal engaged personally supervising the construction of the Dam on Mullai Periyar river. Once, he felt thirsty and called a shepherd Ankur Rauther who gave him milk from the udder of the sheep. The Maharaja felt happy and gave him title over extensive forest lands which were sold to landowners in Tamil Nadu by his descendants. Now, it was converted into cardamom or tea plantation with the help of cheap labour. The British developed these areas as summer resorts. Now, these areas come under Munnar.