森嚴(yán)壁壘
strongly fortified; strictly defined line of demarcation between two schools of thought or two rival factions
早已～，更加眾志成城。(毛澤東詞《井岡山》)Already our defense is iron-clad,Now our wills unite like a fortress.(Mao Zedong’s poem Mount finggang)
森嚴(yán)壁壘sēn yán bì lěi
形容軍事上戒備嚴(yán)密，也比喻界限劃得非常嚴(yán)密。strongly fortified, closely guarded