After the close of the Sangam era, from about 300 to about 600 CE, there is an almost total lack of information regarding occurrences in the Tamil land. Some time about 300 CE, the whole region was upset by the appearance of the Kalabhras. These people are described in later literature as 'evil rulers' who overthrew the established Tamil kings and got a strangle hold of the country. They did not leave many artefacts or monuments. The only source of information on them is the scattered mentions in Buddhist and Jain literature.