"Your population must have Homes to live in. Upgrading homes provides more living space and increases your city's Population Limit."
|Level||Population||Food||Wood||Stone||Metals||Base Upgrade Time|
Homes give you population which allows you to build resource buildings and train. There are several ways to get mroe population. Firstly you can build more houses or upgrade your existing houses. Please note that it is only recommended that you have 4-6 houses which will give you ample population to train continuously. The other way is by decreasing your tax rate, increasing your happiness and increasing your idle population. When you are strong enough, you may want to look at decreasing your tax to zero.
When your Great Dragon Keep reaches level 20 it gains a special ability called Dragons Roar which raises your population by 20K for 24 hours. The first use is free but you will need to use rubies every time you want to use it again.