Pallipadai is Tamil name for sepulchral shrine. I am not sure when this tradition started but it looks common during later Cholas period (10th and 11th century). I came to know about this when I watched this documentary about Raja Raja Chola few years back. I did not believe this at first, thinking why someone will build Shrine near or on the burial/cremation ground. After doing some research I came across several Siva temples of this nature.
I started my research by referring to Historian and Prof. K.A. Nilakanta Sastry work titled Cholas. In that he was discussing about Pallipadai and its close alignment with Saivism. He discusses about that cult of Deva-raja and how inscriptions highlights the construction of sepulchral temples over the remains of kings and princes. Following is the quote from his book “The Adityesvara at Tondamanad erected as a pallipadai to his father by Parantaka I, the Arinjigai-Isvara at Melpadi built by Rajaraja I likewise to commemorate Arinjaya who died at Arrur, and the Pancavanmadevisvara in Ramanathan Koyil apparently erected by Rajendra I are among the most conspicuous examples of this practice”
In his book he also mentioned about human bones unearthed sanctum sanctorum of several temples during the temple renovation. This practice may be prominent among Cholas but certainly not limited to them. There is one such shrine in Pallimadam for King Sundara Pandya. Prof. K.A. Nilakanta Sastry mentions this practice is very common in most South-Asian countries as well. It was not clear whether it spread from South India or they received from elsewhere.
It can be argued that extreme Saivite groups such as Kapalikas and Kalamukahs performed human sacrifices in remote Siva temple premises. They eat the food in skull and besmear the body with ashes of dead body. They also eat ashes, keep the pot of wine and worship Siva in seated position in those shrines/places. However we cannot attribute the bones found in the Pallipadai temple as remains of these activities. Pallipadai temples are substantiated by inscriptions found in those premises which are expected as it was common practice during later Cholas.
I visited one such Pallipadai (as it stated in Chenglepet District Archealogical Guide) temple near Kanchipuram in 2011. Gangaikonda Choleswarar temple at Koozhampandal is built by Isana Siva Pandita the spiritual guru of Rajendra Chola I. It was built in memory of Rajendra Chola I after his death. It has lot of similarities with Gangai Konda Cholapuram temple. This place close Peru Nagar believed to be regional (Mandal) Head Quarters of Chola Kings during that time. This temple is under ASI, however I could see lot of damages done to the sculptures in recent past (see below. Sculptures plastered with cement recently). I am confident excavation around this temple will yield lot more information.