Because it's something I need to know

[robot_mel]

三皇五帝夏商周 sān huáng wǔ dì xià shāng zhōu
春秋戰國秦漢流 chūn qiū zhàn guó qín hàn liú
三國魏晉南北隋 sān guó wèi jìn nán běi suí
唐宋元明清民收 táng sòng yuán míng qīng mín shōu