Why is the ink on Ran's tomb precious?

The most precious thing is the calligraphy inscription of Moutoulou on the beam Fang on the main wall of Ran's tomb. There are 79 lines in the text, each line is 10, and there are two other lines. The full text has more than 800 words and can recognize more than 350 words. The inscription is official script, which has the calligraphy style of Han bamboo slips and is neat and smooth. This ink is a long writing material second only to Tai Hao's tablet, which is of great value to the study of Koguryo history.