This is the title of a 1982 song by The Clash.
A “kasbah” (it’s an Arabic word, with lots of spelling variations in English) is a type of fortress or citadel in the Middle East, Sahara, and India. The song tells the story of a ban on rock music by an Arab king:
By order of the prophet
We ban that boogie sound
Degenerate the faithful
With that crazy Casbah sound
Shareef don’t like it […]
In response to the ban, the people of the story proceed to “rock the casbah,” meaning play rock music in the king’s palace.
According to Wikipedia:
This scenario was inspired by the ban on Western music in Iran after the 1979 Islamic Revolution.