In a non-fiction proposal you need to be specific. Who did you write this book for? Who is most likely to buy it, and why?
When you submit a book proposal you need to lock off some identifiable, reachable groups
"40 Amazon customers who reviewed author's previous book"
"6,000 followers of the author's blog"
"Those who attend author’s workshops"
"Followers of Osho"
“Subscribers to History Today”
“Traditional jazz music fans”
"Author’s community/network/group is likely to buy 200 copies, there are 200 similar organizations in the USA"
"Holiday makers to Crete with time to read novels set in Greece"
"Author has 2000 Facebook likes"
If your title is for children or YA, give the age group. Select from:
Young Adult 13–18
New Adult 18–25