What might happen to the culture in a country or area that is taken over by a foreign power?

It can be stifled or destroyed, by the invader's wilful policy or simple ignorance,or by the natives adopting the newcomers' ways.

For example, when the Danes, Saxons and otherstook over the former Roman territory in the British Isles they pretty well swept away the Romano-British way of life; and society dwindled into the Dark Ages.

When British & European countries took over much of the African and American continents they thought the locals somehow unsophistated and "heathen" and set about trying to convert them to Christianity - while also treating them in ways that ranged from patronising to downright hostile. This was through ignorane rather than will: they genuinely did not realise their actions were wrong.

The Nazi invasions in WW2 did not seek particularly to over-rule those countries' cultures - apart from those of the resident Jews of course - but deemed the governance was tobe according to the military Dictatorship that was National Socialism.

Nowadays, cultural Imperialism is more social and economic than military, with homogenisedAmerican speech, entertainments, historical revisionism, IT,etc bulldozing all before them; while at the same time fervent Islamicists want everyone else irresepctive of background to live solely to their (theIslamicists')own, very limited,ideology.