Exploration and TL

So I'm making a new campaign that will take place in a very young and alien low tech world that the PCs will be explorers of the mysteries of the world. I have a good idea of the world itself but I don't have a good idea on the TL of the "homebase" of the PCs.



I want a TL or a split of TLs that high enough to have a good variety of tools and able to achieve good social organization, but low enough that they can't explore the world and know it with ease and need talented explorers (AKA the PCs) to go out.



I'm think of the range of TL2-4.

Exploration and TL