全盛
ぜんせい · zensei · JLPT N1 · noun
prosperity
全 — enter 入 on top + jade 玉
Originally written as 入 (enter) over 玉 (jade), depicting a complete, unflawed piece of jade kept in storage. From this image of a perfect jade came the meanings 'whole,' 'complete,' and 'entire.' The top component is sometimes written as 人.
盛 — 成 (chéng, phonetic) + 皿 (vessel)
A phono-semantic compound: 皿 (a dish or vessel) gives the meaning, while 成 supplies the sound. The original sense was grain heaped into a ritual vessel as an offering, hence 'to fill' or 'contain' (chéng). From 'full to the brim' it extended to 'abundant, flourishing, prosperous' (shèng).