std::set of unique ptr range insert

I have 2 data structures which hold a set of unique_ptr like so

std::vector<std::unique_ptr<Entity>> tmpEnts;
std::set<std::unique_ptr<Entity>> tmpSet;

I am trying to perform an insert as shown below but i get errors when i compile. I am new to smart pointers.

tmpSet.insert(tmpEnts.begin(), tmpEnts.end());

tmpEnts is actually a simplification, it actually resides in a std::map<uint, std::vector<std::unique_ptr<Entity>>> entities