This category of literature does not have religion as its theme. To this class belongs the Dharmashastras or the law-books which prescribe the duties for different social groups. They set out punishments for persons guilty of theft, murder, adultery, etc.
The earliest law books is Manu Smriti. It was the first book translated by the British and formed the basis of Hindu code of law.
Arthasastra of Kautilya provides rich material for the study of Indian economy and polity of the Mauryan period.
Works on grammar are also sometimes useful for historical reconstruction. The earliest and the most important work on grammar is the Ashtadhyayi written by Panini, which is dated by scholars to around 700 B.C.
The works of Kalidasa who lived during the Gupta period comprise poems and dramas. The famous among them are Abhijananashakuntalam, Ritusamhara and Meghadutam. Besides being great creative compositions, they provide glimpses of the social and cultural life of the Guptas.
For the history of Kashmir we have an important book called Rajataranagini written by Kalhana (12th AD). Biographies or charitias are very important non-religious texts for writing history. They were written by court poets in praise of their patron rulers. As there is a tendency among them to exaggerate the achievements of the patrons they have to be studied with caution. One such important text is Harshacharita, written by Banabhatta in praise of Harshavardhana.
The earliest south Indian literature is called Sangam literature. It was written in Tamil and is secular in nature. It was produced by poets who joined together in assemblies (Sangam) patronized by chiefs and kings during the first four centuries of the Christian era. The literature consists of short and long poems in praise of various heroes, written probably to be recited in the courts.
It also constitutes the epics called Silpadikaram and Manimekali. The Sangam literature is major source for the study of south Indian society, economy and polity during BC 300 - AD 300. The descriptions given in the Sangam literature are confirmed by archaeological finds and accounts of foreign travelers.