This coin is a Kaiyuan Tongbao, first minted in the 4th year of the Wude reign of Emperor Gaozu of Tang (year 621 AD). It was the most widely circulated round coin with a square hole during the Tang Dynasty. The inscription "Kaiyuan Tongbao" was written by Ouyang Xun, a renowned early Tang calligrapher. Its elegant clerical script established the naming convention for later "Tongbao" coins and holds milestone significance in Chinese numismatic history. The reverse side features an upward-facing moon motif at the top—a classic and most common design for Kaiyuan Tongbao coins. This specimen has been professionally graded and encapsulated by GBCA (Gongbo) as Extremely Fine (EF). Dimensions: diameter 25.0mm, thickness 1.2mm, weight 3.6g. The coin exhibits a smooth, well-preserved patina from long-term circulation, with clear inscriptions, uniform shape, and natural wear. It is an excellent example of material heritage from the prosperous Tang Dynasty.

This is a Kaiyuan Tongbao coin, first minted in the 4th year of the Wude reign (621 A.D.) under Emperor Gaozu of Tang. It served as the primary square-hole copper currency throughout the Tang Dynasty. The inscription "Kaiyuan Tongbao" was penned by Ouyang Xun, a celebrated early Tang calligrapher. Its official clerical script established the "Tongbao" naming convention for Chinese coinage, influencing currency nomenclature for over a millennium and marking a milestone in numismatic history. A crescent mark appears above the central hole on the reverse side, representing one of the most classic varieties of Kaiyuan Tongbao. Certified and encapsulated by GBCA (Gongbo Historical Coins Authentication) with an Extra Fine grade. Specifications: Diameter 25.0 mm, thickness 1.2 mm, weight 3.6 g. Featuring natural aged patina, the characters are sharp and well-defined, showing moderate circulation wear. This well-preserved piece serves as an authentic relic reflecting the prosperity of the Tang Dynasty.