Literary sources are of two kinds: Religious literature and secular literature. Secular literature are writings that are not religious. These include poems, plays, stories, biographies of kings, accounts of foreign travels and books on science and politics.
Examples of secular literature are Arthashastra by Kautilya, the Indika by Megasthenes, poems and plays by Kalidasa, accounts of Fa Hien and Hieun Tsang and Sangam literature.