If you are struggling to understand the history and social movements related to your policy issue, I suggest going to a background information source to see if there is an entry on your specific or broader context policy topic. Often encyclopedia articles will provide the historical grounding of an issue that will help answer these questions and provide you with a jumping off point for further searching.
Try the background sources listed earlier in this guide, like Sage Knowledge, and these encyclopedias are specifically focused in these areas as well: