How to write about the history of a new line of research in a grant application?
Your goal isn't to write a history per se but to support future research funding. Keep that in mind. There may be only a few papers, but there may be many ideas. I suggest you focus on those ideas and, especially, what they suggest for the future. 

Some things in the new field have been settled, but, I suspect, many questions remain unanswered, suggesting future lines of inquiry. Mention both of these things - what we know now and what we need to explore. 

So, focus on the ideas, not the specific papers that contain them.