lì shǐ shàng / duō cì / tiān rán dòu / de / bào fā / gǎi biàn / le / shì jiè / rén kǒu / de / fēn bù

历史上多次天然痘的爆发改变了世界人口的分布。

In history, multiple outbreaks of smallpox changed the distribution of the world's population.