I hope you can help me. I am not new to making maps. I have made hundreds! All end up in the trash can. So I come here hoping the I can find some much needed help.

I am trying, emphasis on trying, to create a map for my novel. The story timeframe is the 1500's. The world has been created with two halves. The northern half is the icelands, the southern half is much more temperate but not tropical.

I would like to have a natural barrier separate the two regions but other than having a tall mountain range running east to west , I haven't came up with anything.

Since people travel by foot with only the occasional traveler using a horse. What would be a good scale to use for my map? And I don't think it possible to go from a very cold region to a warmer one without transitions, so on my map can you suggest what the zones could be?

I can't seem to get anything going with my map. Help is desperately needed.

Thank you.