Kashmir Shaivism is an ancient system of philosophy. It has a large number of Sanskrit works and the most important of them is Shiva Sutra. Shiva himself is supposed to have revealed it to Vasugupta (who belonged to the 8th or 9th century CE). Vimarshini (glss), vartika (an explanatory text), and Vimarsini (a critical comment) are all available in Shiva Sutra.
The system deals with Shiva, Shakti, Nara called Trika (triad). The relevant literature has been classified into Agama Shastra, Spanda Shastra and Pratyabhijna Shastra.
The main principles of the system are enshrined in Spanda Shastra which has texts like Spanda Sutra and Spanda Shastra based on Shiva Sutra. Kallata, who belonged to the 8th or 9th century CE, has written a vritti called Spandasarvasva on Spanda Sutra. Commentaries on Spanda Sutra have also been written by Ramakantha, Utpala, Kshemaraja and others. Kallata regards the system as pure revelation.
There is also another Kallata, a great Tamil poet, belonging to the Tamil Sangam age. He wrote a text called Kallatam. He also wrote other works such as Thirukannappadevar Thirumaram and Tholkappiya Urai. He wrote poetry in praise of the chieftains and the Pandya king of his time.