I remember getting my hands on a book titled:
"Christians Of Kerala - History Belief & Ritual Among The Yakoba" by
Unfortunately never got the chance to read it so cant say much about it. The author is a sociologist, who seemed to be making a personal journey of exploration (identity initiated I suppose) through the research she has reported in the book. My dad didnt think it did a lot of justice to the historical aspect per se. I am sure it will be an interesting starting point though!
Hope this helps. If you do eventually get a detailed historical account please do let me know too. I have been told so many stories (home-taught faith education). Word of mouth accounts passed through generations about the arrival of the Syrian Orthodox faith in AD 52 and of the struggles between the SO christians against the Portuguese who tried to enforce the Catholic faith when they set about annexing S. India. Will be great to actually associate these to referenced, researched accounts :-).