Tángcháo / de / huángdōu / Luòyáng / hé / Cháng'ān / dōushì / dāngshí / shìjièshàng / zuì / fánhuá / de / chéngshì

唐朝的皇都洛阳和长安都是当时世界上最繁华的城市。

The Tang Dynasty's imperial capitals Luoyang and Chang'an were both the most prosperous cities in the world at that time.