If you say that somewhere is a hotbed of an undesirable activity, you are emphasizing that a lot of the activity is going on there or being started there.
例句
...a state now known worldwide as a hotbed of racial intolerance.举世皆知现在是滋生种族褊狭的温床的国家
英汉词典释义
n.
(坏事、暴力等的)温床
a hotbed of intrigue阴谋的温床The city is a hotbed of crime.这个城市是犯罪的温床。
英英词典释义
Noun
1. a situation that is ideal for rapid development (especially of something bad);
"it was a hotbed of vice"
2. a bed of earth covered with glass and heated by rotting manure to promote the growth of plants