Please remember every history is scoring If Historiography is taken care of. The father of modern history E.H.Carr says; 'History is names, dates and events.' Rest is legend. Whatever History subject you're going with keep these three rules of Historiography in mind.

US History/European/British: Names and events to remember would be difficult If you have not a background in it. It has relevancy with IR, however, these are two very different fields and one can't say US history would help you in IR.

Islamic History: It's lengthy but very interesting, If you remember the Arabic names of people, cities and major events this is the best history. It's divided between many sections that makes it to remember easily.

Indo-Pak History: That deals with subcontinent and its dynasties starting from Qasim (712) to till date. You'd have to read some good books minimum 5 to cover it. Then you'd have to remember the complete outline of dynasties on your finger tips. Then comes the great rulers among every dynasty to look for their administrative, social, religious reforms their defense and foreign policies.

Now it's you who has to make it scoring.