"Historiographical mapping" is a phrase the Americanist Laura Westoff uses to describe the complex metacognitive moves historians make as they navigate through primary and secondary sources on their way to asking new research questions.
Westoff identifies four categories or modes of inquiry historians use when creating historiographical maps: sourcing, contextualization, close reading, and corroboration.
Here are some suggestions about ways to go about building your own historiographical map of your project.
What primary and secondary sources have scholars used to interpret the past in your general topic area? How have they used these sources in constructing their arguments?
Start with: a few monographs or substantial articles on your general topic area. Generally, you can find these in the bibliographies of subject encyclopedia entries, in published annotated bibliographies, or in online curated bibliographies like Oxford Bibliographies Online.
Look at time and place of publication and explore the work(s) of the author. What can this tell you about the monograph?
Deconstruct each monograph in terms of its sources. In other words, how did the author use the sources?
Compare and contrast the sourcing information for the monographs. What was going on in the world, in the discipline of history, at the time that might explain any differences you see? What are the multiple approaches historians have taken?
What does the author actually argue? How would you evaluate that argument?
Compare arguments. Where do the arguments overlap? What accounts for disparities?