The historical documents about Germanic people are the Battle of Gaul by G.J. Caesar (BC 100 ~ 44) and the Germanic Local Records by P.C. Tacitus (about 55 ~ about AD 120). These two books record the historical facts before the founding of Germany. According to records, the earliest Germanic law is only a tribal habit, and there is no obvious difference from moral norms. Although the customs of different tribes are different, they are basically the same. After the Germanic invasion of Rome, they practiced individualism, that is, tribal customs were applied to tribal members and Roman law was applied to conquered Roman subjects, so Germanic law and Roman law gradually merged. In the 5th-9th century, Germanic kingdoms successively compiled written laws according to their own habits, that is, "barbarian codes". For example, the eurich Code of the Visigoth Kingdom at the end of the 5th century, the Salik Code of the Frankish Kingdom at the end of the 5th century, and the Lombard Decree Collection of the Lombard Kingdom in the 7th century. Salik code is the most important and has been studied the most (see color map). Apart from Anglo-Saxon law and the laws of northern Germanic tribes, most of these codes are written in Latin, and some Roman law terms are also used. They do not stipulate the general rules that members of society should abide by, but only record the judgments of some specific cases. In addition, there have been decrees issued by kings, such as Charlemagne (768 ~ 8 14) of the Frankish kingdom, which issued a large number of decrees, which were applicable to the residents of the whole country. Since the 9th century, with the gradual formation of feudal system and the division of Charlemagne Empire, individualism has gradually changed into territorialism. These feudal methods developed on the basis of the combination of Germanic law and Roman law are applicable to all residents in this area, regardless of nationality and nationality.