Koyi Thampuran was the title of the Prince Consorts of the Queens and Princesses of Travancore. The Koyi Thampurans' gained prominence and prestige in Kingdom of Travancore as they were the fathers of the then reigning Kings. In Travancore, there were ten clans of Koyi Thampurans. The most ancient were the ones settled at Kilimanoor (in Attingal); others were Kirthipuram (in Mavelikkara), Pallam (in Kottayam), Paliyakkara (in Thiruvalla) and Nirazhi (in Changanasseri), Ananthapuram (in Karthikapalli), Chemprol (in Thiruvalla), Cherukol, Karamma and Vatakkemadham.
After the invasion of Malik Kafur in 1310, Veera Udaya Marthandavarma was forced to abdicate in favour of the Princesses sent from the Kolathiri Royal Family (also a family descending from the Cheras and Ay) called Attingal and Kunnumel Ranis. The line of kings after Ravi Varma continued through the Marumakkathayam law of matrilineal succession of Nairs. Thus, the Southern Chera-Ay dynasty adopted Matriarchy/Marumakkathayam after 1310. With the adoption of Attingal and Kunnumel Ranis to Venad in 1310, only the sons of the Attingal Rani had the right to become the King and the Kings own sons from non aristocratic Nair women did not have the right to become the next king. The Attingal Queen started adopting prince and princesses from the other Matriarchal dynasties of Kerala from the Koalthiri dynasty to the Venads Chera-Ay Royal houses. Soon after Ravi Varma's death two princesses were adopted from the Kolathiri Royal family and installed as Ranis or Queens at Attingal. The Venad Royal family continued thus in the female line. Whenever there were no females to take forth the line, princesses were adopted from the Kolathiri family, the latest adoption being in 1994. This tradition was reciprocal with several adoptions from the Venad Family also going into Kolathiri. The Koyi Thampurans were aristocratic men who were chosen to become the Prince Consorts or husbands to these Attingal Ranis.
The females of the royal family are styled as the "Queens of Attingal" with the titles of Attingal Mootha Thampuran(Senior Queen of Attingal) and "Attingal Elaya Thampuran"(Junior Queen of Attingal) and "Attingal Kochu Thampuran"(First Princess). According to historians, the Koyi Thampuran's or the Prince Consorts were selected from 10 major aristocratic houses or palaces which are closely related to the Travancore Dynasty. The Prince Consorts of the Senior and Junior Maharanis are known as the Valiya Koyi Thampuran and Kochu Koyi Thampuran respectively.
Even though the Koyi Thampurans attained prestige through marriage to the Attingal Ranis, the historians state that they were considered inferior to their spouses and their royal children. They weren't allowed to travel by the same vehicles and were not allowed to be seated next to the Queens and Princesses who were their wives. They were also supposed to provide their royal spouses and children all marks of respect and could only address them with the proper royal titles in public. They had no part in the Kingdom's administration even though couple of them tried to exert their influence illegally on their spouses. Compared to the status of the Travancore King's non aristocratic Nair spouses Ammachi Panapillai Ammas, the Koyi Thampuran's status were much better and had high degree of public respect. By the 20th Century, a lot of changes had taken place in the status of Koyi Thampurans. In 1924, Maharani Regent Sethu Lakshmi Bayi chose to seat her consort next to her in the Court despite some oppositions. And with the wedding of Karthika Thirunal Lakshmi Bayi, the sister of Maharajah Sree Chithira Thirunal, with the then Capt. G. V. Raja almost all of those restrictions were lifted. Even then, the Koyi Thampurans weren't allowed to meddle in the administration. Maharajah Sree Chithira Thirunal eventually did handed his brother-in-law, Capt. G. V. Raja, duties & position in the then royal government.