zhōu Left: Water 氵, right: prefecture 州 (Sandbanks 丶 in the river 川 separate the prefectures.) When there is a lot of water at the sandbanks in the river, the prefecture turns into: an island.
zhōu Three sandbanks 丶 in a river 川 (They are administrative units within one country) You can get via sandbanks in the river from prefecture to prefecture.