Gǔdài gōngchéng shí cháng yòng yúntī fānyuè chéngqiáng.
In ancient times, scaling ladders were often used to climb over city walls during sieges.
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history
云梯 was invented during the Spring and Autumn period, attributed to the craftsman 公输般. The name literally means 'cloud ladder' because it reaches so high it touches the clouds.
