Issued by the Yunnan provincial post in 1929 to commemorate the state burial of Dr. Sun Yat-sen, this green 4-cent stamp depicts the Mausoleum on the Purple Mountain in Nanjing, an iconic symbol of republican memory and national unity. Overprinted vertically in black with “雲南省貼用” (for use in Yunnan Province), this local issue revalidates a central government commemorative design for provincial circulation. Printed by gravure in olive green with line perforation 14, this stamp is listed as Scott YU26, Michel CN-IM-YU 26, Yvert 26, Stanley Gibbons CN-IM-YU 26, and China Stamp Society CN-IM YN27. The present item is a full unmounted mint sheet of 5x6 (30 stamps), showing pristine original gum and marginal inscription “CHINESE BUREAU OF ENGRAVING AND PRINTING” at the bottom. Slight gum disturbance and hinge remnants are visible in the lower margin, but overall condition is exceptional with sharp perforations and rich color. Estimate "$230 – 270"