There are two types of sources to know history .first is archaeological & second is literary source. Literary sources are the authentic source to know history. 

Archaeological source inclusde material remain , megalithis , pottery ,coins , inscriptions, languages . 

Whether literary sources are classified in two parts first is religious literature and  secular literature. 

 Example of archaeological source - material remain - forms of houses , kind of cereals , tools,  & ringwells used for toilets ,or dup garbage .

Megalithis - the life of people of post iron age ( the largest collection of iron tools weapons found there)

The use of iron starts 3000 years ago but evidences are found 2500, years ago. 

Pottery - Red & black pottery used in Indus valley civilization.  & grey ware in Vedic society . 

Coins are very useful to know history because it tells the time period of any kingdom ,name of king , God ,culture ., language etc . And also tell us the economic history of any empire . Gupta has the largest number of gold coins due to good trade and commerce . 

And now religious source examples - puranas mahabharata ramayana Jain & Buddha literature . 

Puranas tell us genelogical of any king. Mahabharata is also called jayasamhita  when it has 8800 verses and bharat when it has 24000 verses and at last when verses became 1 lac it is called MAHABHARAT. OR Satsahshri Samhita .

Ramayana had 12000 verses at early but after verses became 24000 . So it written after Mahabharat 

Jain and Buddhism 's  religious book had convey only personalities and incidents . It is written in Pali language which is the common language of Magadha & southern Bihar . It not only tells the story of Buddha but also tell about the Buddhist king who ruled  in eastern UP And northen bihar. It compiles in 2nd century BC in SHRILANKA. Buf vihit part convey about Buddha 's yoga matters .

And Jain literature is written in prakrit language . Finally his compilation in 6 century AD at vallabhi in Gujarat.  

Secular literature- class of secular literature Dharmasutra , smriti, Jeevan Natak & southern India literature refers to the Sangama sahitya literature.