国

Outer enclosure radical - the big square that wraps around the inside, written as the first two strokes (top-left, top-right + right side) and closed on the last stroke. The indexing radical for 国; 囗 marks the bordered territory of a nation. Distinct from the smaller 口 (mouth) it visually resembles. Same family: 困 (trapped), 因 (because), 园 (garden).

Inside 玉 - jade, the most prized substance in Chinese culture, symbol of imperial authority and national treasure. The simplified 国 reads as 'jade within borders' - a nation as a precious treasure protected by walls. The traditional 國 had the more martial 或 (territory/possess) inside instead.