How the name should be understood has been disputed, but Chinese historians have concluded that during the Tang dynasty, the area of modern-day Shanghai was under the sea level, so the land appeared to be literally "on the sea".
如何理解这个名字一直有争议，但中国历史学家得出结论，唐朝时，现在的上海地区处于海平面之下，所以这片土地看起来确实“在海上”。