Sankagiri Fort was an important military base for Tipu Sultan and later for the British army. This is because only one side of the hill is climbable, as all the others are too steep to climb. This has a death well, granary, two oil go downs, one explosives godowns, two mosques, two Varadharaja Perumal temples, former British Army administrative buildings, and cemeteries formerly used by armies that were stationed at the fort. Dheeran Chinnamalai, the Kongu Chieftain who rose against the British East India Company was hanged by the British in this fort.
Following the decline of Chola rule in the 13th century, the Thanjavur came under the rule of the Pandya Dynasty who ruled for about a century. Following the invasion of Malik Kafur, the Tanjore country fell into political and economical disorder. The rule of the Delhi Sultanate lasted for half a century before Pandya chieftains reasserted their independence. Soon afterwards, however, they were conquered by the Vijayanagar Empire. The supremacy of Vijayanagar was challenged by the Nayaks of Madurai who eventually conquered Thanjavur in the year 1646. The rule of the Thanjavur Nayaks lasted until 1673 when Chokkanatha Nayak the ruler of Madurai invaded Thanjavur and killed the ruler of the mighty Vijayanagar Empire, Vijayaraghava (Vijayaraghava Nayaka of Tanjavur in India).
Chokkanatha placed his brother Alagiri on the throne of Thanjavur. But within a year the latter threw off his allegiance, and Chokkanatha was forced to recognize the independence of Thanjavur. A son of Vijaya Raghava induced the Bijapur Sultan to help him get back the Thanjavur throne. In the year 1675, the Sultan of Bijapur sent a force commanded by the Maratha general Venkoji to recapture the empire from the new invader. Venkoji defeated Alagiri with ease, and occupied Thanjavur. He did not, however, place his protegee on the throne as instructed by the Bijapur Sultan, but seized the kingdom and made himself king. Thus began the rule of the Maratha Empire over Thanjavur.
During this period, Chettiar community helped the Thanjavur kingdom to mobilize money to fight against invaders. Hence Marathas ordered to convict all the Chettiar men. To avoid losing succession in the community, elderly wise men arranged to gather 500 children of Chettiar community and confidentially moved them to Sankagiri region. These people were called Five hundred Kongu Chettiars. Chettiars being devotees of Lord Shiva built their Shiva temple near Sankagiri in a place called Sunnambu Kuttai (Lime stone Pond). The temple Lord Shiva was named Kopineshwar Temple, with Angayarkanni (Lord Meenakshi of Madurai).
The remains of decrepit temple Kopineshwar-Angayarkanni temple is still found on the way to Edappadi. This dilapidated temple was identified in 1982 by Viswanathan Chettiar of Coimbatore. He has identified the boundary of the temple, sanctum sanctorum of the temple and few broken granite idols. The adjacent land was cultivated, but this temple land was isolated and nobody wants to misuse this land due to its mystical power.