China, 621-718 AD., Tang Dynasty, early Kai Yuan type, 1 Cash, Hartill 14.1.

China, Tang Dynasty (618-907), Tang Dynasty, early Kai Yuan type, issued ca. 621-718 AD.,
1 Cash (24 mm / 2,77 g), cast, square central hole,
Obv.: 開 元 通 寶 , Kai Yuan Tong Bao ("The Currency of the K'ai-yuan Period" or "The Inaugural Currency") , top-beneath-right-left of central hole. The "jing" component of "Kai" does not touche the hole, the head of Tong is small, the top stroke of "Yuan" is short, the two stokes in the middle of "Bao" do not touch the verticals.
Rev.: plain (square center hole).
Hartill 14.1 (rarity 14, very common) ; Schjöth 312 ff ; FD 672 ff .

Kai Yuan meant “to open a new beginning”, and it did indeed set new standards for casting, legend, style and shape, that were followed in almost all later dynasties. The legend of Tang coins consisted of four characters read top-bottom-right-left.