The Thiruvalangadu plates issued by Raja Raja Chola (AD 1012-1044) are helpful for studying Kerala history. The inscription describes the invasion of Vizhinjam by the king thus: "Ee sooryavamsha vibhooshanante dandadhikari, samudraparikhavum thungabhasuraprakaaravum anyaveeragamyavum vijayadevatha nithyasankethavumaya Vizhinjam swadhikarathilaakki".
The plates describe Raja Raja Chola as "Kanthalloor Chalai Kalamarutha Rajaraja thevar" meaning the king put an end to the food distribution, Veda learning and weapon training at the Kanthalloor Sala. According to the inscription, devadasis were sold to temples. The myth that Parasurama created the state by throwing his axe too finds place in the plates.