分久必合，合久必分

fēn jiǔ bì hé , hé jiǔ bì fēnfenjiubihe,hejiubifen

1. (lit.) that which is long divided must unify, and that which is long unified must divide (proverb, from Romance of the Three Kingdoms 三國演義|三国演义[San1 guo2 Yan3 yi4])
2. (fig.) things are constantly changing

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