Ethiopia Boreal Deity Challenge

Obviously with 21 civs the map is quite cramped, but your starting position, nestled up against the ocean, has a bit of space from your opponents. Unfortunately most that space is ice, and you'll probably have trouble finding a decent spot for even a second city. One option is to go OCC for most the game and expand later, if you want to take that path probably it's worth following the river 2SE for a more inland city. Religion is another good approach, you should have little trouble founding, and if you do it quickly you should have little trouble getting the "Dance of the Aurora" pantheon, which gives faith for tundra tiles, a great bonus for this map.

I've been looking for maps which are "easy to survive, difficult to win" and I think this map fits the bill. It only takes a few bribes to keep the AI off your back but actually expanding seems difficult.