What font was used for official documents during the Song Dynasty?

It is speculated that the official font of the Song Dynasty is regular script

The development history of Chinese regular script can be divided into four periods: the embryonic period of regular script - Qin and Han Dynasties, and the development period of regular script - Wei and Jin , Southern and Northern Dynasties, the period when regular script flourished - Sui, Tang, and Five Dynasties, and the period when regular script maintained its maturity - Song, Yuan, Ming, and Qing Dynasties.

The font we call "Song Dynasty" began to gradually separate from calligraphy fonts in the Southern Song Dynasty, but it was only a transitional period between printing fonts and calligraphy fonts. Later generations called it "transitional imitation of Song Dynasty" Style" such as "Girl Fish Mysterious Poetry". In the Ming Dynasty, with the rapid development of printing technology, printing fonts finally formed the final version we call "Song Ti" today.

Extended information:

Regular script is also called Zhengkai, Zhenshu, and Zhengshu. It gradually evolved from the official script founded by Cheng Miao, becoming more simplified, horizontal and vertical. "Cihai" explains that it "has a square shape and straight strokes, which can be used as a model." Hence the name regular script. It began in the late Han Dynasty and has been popular to modern times.

The emergence of regular script closely followed the rules and regulations of the Han Dynasty, and pursued the further development of physical beauty. At the end of the Han Dynasty and the Three Kingdoms period, the writing of Chinese characters gradually changed from waves and hens to apostrophes and swivelings, and " Strokes such as "side" (point), "plunder" (long stroke), "peck" (short stroke), and "lift" (straight hook) make the structure more rigorous. Such as "Wuwei Medical Slips", "Juyan Han Slips", etc.

The characteristic of regular script is its neatness and neatness. It is a model among fonts, so it is called regular script and has been used until modern times.

Reference: Baidu Encyclopedia - Regular Script