The Tharisapalli copper plates document Venad ruler Ayyanadikal Thiruvadikal's donation of a region and its administration to Tharisapalli church in Kollam established by Marsapir Imbo. Venad Adikal was a ruler under the Kulasekhara king Sthanu Ravi Perumal and the donation was in the fifth year (AD 849) of the latter's reign.
It says: "Ee aandil Venad vazhunna Ayyanadikal Thiruvadiyum udyogasthanmarum prakrithiyum manikiramavum anju vannavum punnathalapathiyum koodi alochichu kurakkeni Kollathulla Eshodathapir cheyyicha Tharisapalliku Ayyanadikal Thiruvadi kodutha viduperu".
Though the plates belong to Kollam, these title deeds are kept at the Syrian Christian Church, Kottayam and Marthoma Church, Thiruvalla and are called "Kottayam cheppedukal". These are the first important inscriptions in the state of which the exact date was found.
As per historic documents, the first Venad ruler is the Ayyanadikal who issued these title deeds. The ancient inscriptions also provide information on Kerala's Muslim community. It has references to Anchuvannam, Manigramam, both trading organisations, Arunoottavar, labour tax, sales tax and vehicle tax. According to the inscriptions, Thalakkaanam, Onikkaanam, bamboo for roofing, chantanmattu, meniponnu, poliponnu, eravu choru and kudanazhi taxes were imposed on the Ezhava and Vannar communities.
Marsapir Imbo would have been a trader organisation leader. According to the cheppedukal, Elavar (Ezhava), Vannar, Vellalar and Thachar families were donated to the church. The inscriptions prove that Venad was a province under the Kulasekhara dynasty.
There is a version that Tharisapalli was the church of "tharithaikal" meaning foreigners. The documents which were recorded as lost by Charles Swanston were recovered in the efforts of Lord Macaulay. The documents were republished by Dr. Herman Gundert in the Madras Journal of Literature and Science. The last portion of the first inscription and the first portion of the second inscription are yet to be recovered.