UU (btw what does UU stand for?) = refugees. The refugees can go in your city and destroy your culture. As they bring another culture with them.
related items:
splitting relions (catholic and protestanism)
decrease of culture border
unhappy faces
If you kill refugees AI's will get furious on you
From the link Vinstafresh gave us. post 19
related items:
splitting relions (catholic and protestanism)
decrease of culture border
unhappy faces
If you kill refugees AI's will get furious on you
Next they let loose on the Visigoths, under Athanaric on the Dniester River, and forced them to flee into the Roman Empire. This event marked the first time a peoples had ever been forced into mass migration. It is also, more important to note, signified the beginning of a barbarian presence in the Roman Empire that would eventually not be so much assimilated, as it would dominate.
From the link Vinstafresh gave us. post 19