With the unification of China under the Qin, China was no longer divided into various states constantly fighting each other: where previously the Mohists proved to be an asset when defending a city against an external threat, without wars, and in particular siege wars, there was no more need for their skills. The "Stanford Encyclopedia of Philosophy" suggests, in addition to the decline of siege warfare, "... the major factor is probably that as a social and philosophical movement, Mohism gradually collapsed into irrelevance. By the middle of the former Han dynasty, the more appealing aspects of Mohist thought were all shared with rival schools.