The Mar Thoma Nasranis (Saint Thomas Christians) are one of the earliest Christian communities in the world. Numerous patristic writings and ancient documents bear witness to the early presence of the Christian faith in India. Apart from the presence of granite inscriptional tablets, grants engraved on copper plates and Pahlavi inscribed crosses, not many native documents are extant from the pre-Portuguese period. In this paper, I would like to focus on photographic images of some of those valuable inscriptions and discuss their relevance to the historiography of Indian Christianity. Granite inscriptional tablets and the Pahlavi inscribed granite crosses narrate the history of the Saint Thomas Christians in India, the evolution of an inculturated native Christian community and the conflicts related to religio-colonial invasion and suppression. Pahlavi inscribed bas relief crosses tell the story of the migration of Christians from Persia. Interestingly, copies of the crosses show cultural adaptations of South Indian artistic elements. These crosses are evidence of the evolution of a native icon of worship. The inscriptions are found on granite tablets, crosses and altar wall. They are in East and West Syriac, Pahlavi, a middle Persian script and in 'vattezhuthu', an ancient script of the local Malayalam language. They consist of the edict of a local king, accounts of events, prayers or liturgical formulae and funerary inscriptions. The edict of Thazhekkad of the 8-11th century, recording of a local king giving favours and privileges to the Christians inscribed on a granite slab, is one of the most ancient inscriptions still extant. The inscriptional tablet at the ancient church at Muttuchira and the pedestal of the open-air rock cross at the ancient church of Champakulam are examples of inscriptions which record significant events. In addition, there are many funerary inscriptions, one of which, found at the church at Udayamperoor and concerning the death of a Christian king, throws light on the existence of a Christian dynasty in South India. There are several Syriac language inscriptions which range from the ancient Judeo-Christian usage of 'Yah' at the Church at Koratty to inscriptions of Latinised theological content. These treasures of ancient Christianity in India call for research from multiple academic disciplines.