History of Maratha Empire is studied on the basis of available historical sources which include written documents, material sources and even oral traditions. It is important to evaluate these sources considering their authenticity and reliability. Few inscriptions and coins from the Maratha period are also available. Oral traditions were also eventually penned or collated by writers. But the largest source for studying Maratha history is written documents. A broad categorization of these literary sources can be done as under -

Public Documents
These are documents and letters issued from various administrative offices regarding land and revenue, institutional grants, decrees, court orders, panchayat decisions and so on. These also include records maintained in courts and administrative offices of various emperors, jahgirdars, watandars and so on, including inter-office communication etc. The main objective behind these documents is not to inform people about the history but they are only prepared in the course of administering the region.

Historical Accounts
This covers accounts written by people having access to official records, thereby, considered to be more authentic than Historical Literature. So this includes, but is not limited to court records, Shakavalis, official biographies and collections of public or historical documents. The primary objective behind these records is to let others know about the history.

Personal Records
These are the personal notings, diaries or travelogues recorded by individuals in their own capacity.

Historical Literature
This includes literary work which is not 100% history but has some important aspects of history woven into it. It includes poems, bardic compositions, plays and such other literary content with fair amount of history embedded in it. This also includes biographies written by unofficial biographers.

When a document states that it is written by someone or written by someone for someone and is actually found to be as per that, then it is said to be authentic or genuine. If someone prepares a document to make it appear as if it was written by Shivaji, or for whatever reasons, changes some part in an authentic letter, such letter would be considered fake. While determining authenticity, it is important to know that authenticity of the document is different from correctness of contents of the document.

There are two types of authentic documents, original and copies. Original are those which bear the original signature and stamps of issuing authorities. Copies are those which are prepared later from such original documents but are still authentic from a historical perspective. The copies can also differ as those made by the writer of the original document and those made by someone else. Those can be hand copies or photo copies made at a much later date. Photo copies still retain most of the pecularities of the original letter, except probably the paper and ink quality.

Copies can have flaws that creep in while making the hand copy. These however, do not impact the authenticity of the document, though they may affect the content. The key aspects that determine the authenticity of a document are as under -
a. Paper and Ink
b. Seal and signature
c. Layout and writing
d. Date
e. Language and Script
f. Handwriting
g. Historical content
h. Relevance with similar documents

For more details on authenticity, please go through Annexure 1 from Shree Raja Shivachhatrapati, Khand 1 Bhaag 2 by Shri Gajanan Bhaskar Mehendale.

These sources can also be sliced as contemporary or from later period, the former holding better value in terms of reliability in most cases. Such slicing is always relative to the time period of the document and the content to which it relates.

For example, a document dated in 1740 CE refering to an incident in 1680 CE makes it a document from later period. While a letter from 1680 CE mentioning an event in the same year or close to that year makes it a contemporary document, and thereby generally held to be more reliable.

Even the author of a document can become a deciding factor while establishing whether a document is contemporary or from later period. For example, someone who has personally been a part of or has seen events in 1680 CE may write them down fifty years later in 1730 CE, still making it a contemporary document.

Though the reliability of later period documents is lesser than the contemporary ones, they can also shed light on some interesting facets of history. This is especially true in case of oral traditions which flow across generations till they are documented by someone later.

Reliability of a document is primarily dependant on three things -
a. Source Type
b. Authenticity
c. Time Period

Of the given source types, Public Documents are generally considered to be most reliable, especially if they are contemporary. This means that they are documents of the first grade in terms of reliability. Historical Accounts and Personal Accounts may contain some amount of subjectivity or bias on the part of the person writing it or for whom it was written. So they are normally treated as second grade documents in terms of reliability. Historical Literature falls in the third grade due to its free form and creative nature. But it also may contain some very interesting aspects of history.

As a general rule, a first grade document will be relied upon in case of a disagreement with a second or third grade document. But when a first grade document is not available to support a second or third grade document, that reference cannot be discarded just because it is not first grade. Second and third grade documents are also useful in highlighting events which do not have supporting first grade documents.

Authenticity of a document can be decided on the basis of points described in the relevant tab. The good thing about this parameter is that if the right methods are applied, a document can be said to be either authentic or fake. There is little room for an in-between possibility.

As a general rule, any contemporary document is more reliable than a document from a later period. But in specific cases, the source type is also important while evaluating the reliability.

These sources are in many languages, Indian and foreign, making the effort of translating and collating them, quite humongous. The amount of material available in all these languages makes it a formidable study. A quick classification on the basis of language would be as under -

Indian languages - Sanskrit, Marathi, Hindi, Kannada, Tamil, Bengali, Rajasthani
Foreign languages - English, Dutch, Portuguese, French, Farsi

Along with the different languages there are primarily four scripts used in these documents namely - Modi, Roman, Farsi and Devanagari. Most of the documents are in Farsi and Modi though many forign sources are in Roman script.