Fortune was in the east of bank thirty years ago, but turns to west when thirty years has passed.

解释 ( paraphrase )
三十年前风水在河的东面，而三十年后却在河的西面。比喻世事变化，盛衰无常。
这条谚语说明世界有时变化太快超乎了我们想象，而使我们无法预料到将来的状况。

This proverb points out that the world is changing so fast that it is always beyond our expectation; therefore, we can’t precisely predict how it becomes in the future.

风水（fēng shuǐ）：旧时指宅基地、墓地等所处的地理形势。迷信认为风水的好坏可以影响家族的兴衰吉凶。
                            Fengshui refers to the location of a house or tomb, supposed to have an influence on the fortune of a family; geomantic omen.

造句 ( example )
五六年前，他还吃不饱穿不暖，而现在居然住上了三层小楼，真是“三十年河东，三十年河西”啊！