VV4 iPhone population stuck at 30

I can't seem to get my population past 30. I have all 4 huts and all puzzles and am maxed out in all technology except alchemy and science (both level 2). Any help would be appreciated. Thanks.

There are more than 4 huts total, but only 3 population huts. Have you built all 3 of those?

ohh maybe not. Where do I find the other huts? I think I built from all the "ruined huts" in the sand area

Once you have the appropriate tech levels, new hut foundations will appear