Another way to upgrade a province after you control it that would go well with the recent changes to church and stuff would be to add a feature to upgrade a province. So if I or my tribe own certain % of province, 50% or 100% we can then build a berm for a sum of resources(not cheap obviously). Instead of giving a bonus to defense strength would give any attacker that attacks into province a time penalty of 2-6 hours? Would give defender more time to respond, read attacks, sleep, whatever they want to do. Would make it so be beneficial to do as it gives time to respond but not a strength bonus as could get annoying to break turtles more.