IMO optionals in CSE are going to stay for atleast one more year (2013) before the Centre approves the new CSM pattern. So what I am going to write here wont be obsolete for atleast one more year.
History optional should be chosen only if one is deeply interested in it. It is a vast subject unlike public administration or sociology or literature or philosophy. Unless one is inquisitive about the subject it becomes tedious to read. People tend to choose optionals like PA or socio or literature etc, even if they dont have any positive interest in them, as they have less voluminous syllabus, as they are easy to score, as they are easy to understand, as study material and coaching are easily available etc. History differs from them on the first two points. So history is normally taken by people who do BA or MA in history or those who are really fascinated by the subject.
So, what to read for history optional from the exam point of view then?
Unfortunately there is no one book which is comprehensive enough, which has everything we need to study. There are many books to read and one has to take the help of internet too. But I will try to present the absolute minimum number of books you have to read which are indispensable. A beginner should first read +1, +2 NCERT books. After that proceed to read the following books.
1. Ignou BA (not MA material) for ancient, medieval, modern Indian history. Most important source of all. There are only very few topics in these booklets which you dont have to study. Otherwise you have to read most of them. It is lucidly written.
2. Gazetteer of India Volume-2 for ancient and medieval Indian history. You need to be discreet enough to leave some topics and subtopics through out the book particularly in political history part as these are not necessary for the exam but very interesting. This book is a good source for the art, architecture, S&T, social life, different sources of history. It is full of facts, there is a risk that some may lose interest in reading history. :-)
3. Medieval India by Satishchandra (both parts). Lucidly written book although biased.
4. Spectrum's A brief history of Modern India. This is a book which is normally studied for GS History. But this is enough for optional history too. It is well written abridged version of Grover and Bipanchandra put together.
5. Jain&Mathur for world history. I observed that some people have a low opinion about this book. But I found it be good from the exam point of view. Buy it.
6. Modern World History by Lowe. A very well written book.
7. Spectrum's Historical Atlas of India. This is not enough. You have to do much more than reading this one. I will write a separate post on how to prepare for map question which carries 60 marks.
Apart from the above books which are absolutely essential, take the help of internet particularly Wikipedia wherever necessary. There are certain other books which some people suggest but which are NOT necessary in my opinion. They are -
1. AL Basham's the wonder that was India - very nice book. Read it if you have spare time.
2. Romila Thapar's Ancient India - well written from Marxist perspective, biased. No need to read. One may hate Romila but none can disagree that she is good writer. :-)
3. DN Jha's book on ancient India - lucid but very biased. Useless to read.
4. Medieval India by JL Mehta (all 3 volumes) - good books but no need to read.
5. Bipan Chandra's two books : Struggle for Independence, India after Independence - very biased and useless books written by a Congress chamcha. Resist indoctrination. Dont forget to perform shuddhikaran on yourself to clean the polluted mind after reading these books. :-)
6. Modern Indian History by Sumit Sarkar -No need to read.
7. Grover's Modern India - Modern Indian history between 18th century and 1905 is given at length in this book. But history after that is rushed through. This is voluminous, full of details. Good book Buy this.
8. Modern Europe to 1870 by CJH Hayes - very nice book. Read it in spare time. If I am not wrong there is another book written by Hayes for history after 1870. I dont have that book.
9. Ensemble's History Atlas - no need.
There are many NBT books on History which makes your knowledge comprehensive like India by Al Biruni, Medieval India by Irfan Habib, Coins, Temples of South India, Temples of North India, a book on Aryans by Romila, Asokan inscriptions, Shivaji, Bhagat Singh, Partition, philosophy of bomb, Tagore and Nehru, etc etc. These books are of very low prices and if history intrigues you then read them in spare time (Not from the exam point of view but just for fun).
One may be wondering, "But what about the coaching material, like Baliyan?" I haven't even seen any coaching material for history but generally speaking coaching material is useless, shallow, unorganised, incomprehensive, written in poor language. So my suggestion would be not to buy any coaching material.
So these are the books to be read. But beginners may be wondering where to start. My suggestion would be to start with old NCERT books for +1, +2. Read them twice as if you are reading a good non-fiction non-acdemic book. Then proceed to read IGNOU material. After that you will figure a way by yourself.
And remember that studying history doesnt mean cramming all the facts. It is more about understanding the perspectives and ideologies, looking through the motives behind actions, understanding the causes behind the social, economic, political, cultural, religious, technological changes (change and continuity!). Dont blindly believe what the author is saying. Indian Marxist historians and Congress chamcha historians are good at twisting the facts into deceptively convincing and false narratives. Try to build your own arguments based on facts against what the author is saying.