What are Strongholds?
Strongholds are fortifications of enemy tribes. Attack them in their own territory and try to get as far as you can. Every successive battle will be more difficult than the previos one. The more you advance, the better your rewards will get!
You can find multiple Strongholds on the map. All of them are populated by non-player opponents of that region (e.g. Domesticar Orcs, Frostblood Orcs).
Lay siege on their Stronghold and fight as many battles as you can. If you win, you will get rewards for respective battle and your battle counter will increase. With every battle your opponents will be more challenging, and the rewards more valuable.
Once you start facing opponents that are too tough, you may consider manually resetting the Stronghold and begin anew, or wait for the next daily reset. With every reset each Stronghold will start at battle 1 again.
Your battle highscore will be saved for each Stronghold, so you can commemorate this moment at their entrance. Improve your regiments and break your own record if you can!
You can also watch the video guide that will introduce you to this feature.