河清海晏

héqīnghǎiyàn
  1. the Yellow River is clear and the sea is calm
  2. the world is at peace (idiom)

CEDICT

黃河的水清澈，大海平靜沒有風浪。比喻太平盛世。《孤本元明雜劇．孟母三移．第一折》：「當時風調雨順，國泰民安，河清海晏，偃武修文。」也作「海晏河清」。

重編國語辭典

Entry Composition

1 河 hé
  1. (bound form) the Yellow River
  2. (bound form) the Milky Way
  3. (bound form) (on restaurant menus) rice noodles 河粉 héfěn

classifiers: 條, 道
2 清 qīng
  1. (of water etc) clear; clean
  2. quiet; still
  3. pure; uncorrupted
  4. clear; distinct
  5. to clear; to settle (accounts)
3 海晏 Hǎiyàn Haiyan County in Haibei Tibetan Autonomous Prefecture 海北藏族自治州 Hǎiběi Zàngzú Zìzhìzhōu, Qinghai