The Jurchen is a Siniform script, that is, the form of its characters are based on those in the Chinese writing system. However, the signs in Jurchen are not derivative of Chinese. The visual similarity is due to that each character is composed of brush strokes, but the way the strokes are combined is different from that of Chinese. Also, as in Chinese, Jurchen characters are highly logographic, and do not give any clue onto the sounds of the words they represent.
Before the 12th century AD, the Jurchen people were a confereration of hunting and fishing tribes in northeastern Manchuria. But from 1115 AD to 1234 AD they rose to power and formed a kingdom called "Jiang" that occupies a large portion of northern China.
The Jurchen also overthrew the kingdom of Khitan (of Inner Asia), but took and adopted the Khitan writing system. Khitan itself is poorly attested and remains undeciphered. Even the Khitan language is unknown.
The Manchurians are the descendants of the Jurchen. The name "Manchu" became the official name of all Jurchen tribes after the 16th century. The Manchurians adopted the Mongolian script (which is a distant descendent of Brahmi) in 1599, and the Jurchen script ceased to be used.