The Germania begins with a description of the lands, laws, and customs of the Germanic people (Chapters 1–27); it then describes individual tribes, beginning with those dwelling closest to Roman lands and ending on the uttermost shores of the Baltic, among the amber-gathering Aesti, the Fenni, and the unknown tribes beyond them.

Tacitus says (Ch. 2) that physically, the Germanic peoples appear to be a distinct nation, not an admixture of their neighbors, since nobody would desire to migrate to a climate as horrid as that of Germania. They are divided into three large branches, the Ingaevones, the Herminones and the Istaevones, deriving their ancestry from three sons of Mannus, son of Tuisto, their common forefather. In Chapter 4, he mentions that they all have common physical characteristics, blue eyes (truces et caerulei oculi = "sky-coloured, azure, dark blue, dark green), reddish hair ( rutilae comae = "red, golden-red, reddish yellow") and large bodies, vigorous at the first onset but not tolerant of exhausting labour, tolerant of hunger and cold but not of heat or thirst.

In Chapter 7, Tacitus describes their government and leadership as somewhat merit-based and egalitarian, with leadership by example rather than authority and that punishments are carried out by the priests. He mentions (Ch. 8) that the opinions of women are given respect. In Chapter 9, Tacitus describes a form of folk assembly rather similar to the public Things recorded in later Germanic sources: in these public deliberations, the final decision rests with the men of the tribe as a whole.


The latter chapters of the books describe the various Germanic tribes, their relative locations and some of their characteristics. Many of the tribes named correspond with other (and later) historical records and traditions, while the fate of others is less clear


After the assassination of Domitian in AD 96, and amid the predictable turmoil of the regime change, Tacitus used his new-found freedom to publish this, his first historical work. During the reign of Domitian, Agricola, a faithful imperial general, had been the most important general involved in the conquest of a great part of Britain. The proud tone of the Agricola recalls the style of the laudationes funebres (funeral speeches). A quick résumé of the career of Agricola prior to his mission in Britain is followed by a narration of the conquest of the island. There is a geographical and ethnological digression, taken not only from notes and memories of Agricola but also from the De Bello Gallico of Julius Caesar. The content is so varied as to go beyond the limits of a simple biography, but the narration, whatever its form, serves to exalt the subject of the biography.

Tacitus exalts the character of his father-in-law, by showing how — as governor of Roman Britain and commander of the army — he attends to matters of state with fidelity, honesty, and competence, even under the government of the hated Emperor Domitian. Critiques of Domitian and of his regime of spying and repression come to the fore at the work's conclusion. Agricola remained uncorrupted; in disgrace under Domitian, he died without seeking the glory of an ostentatious martyrdom. Tacitus condemns the suicide of the Stoics as of no benefit to the state. Tacitus makes no clear statement as to whether the death of Agricola was from natural causes or ordered by Domitian, although he does say that rumors were voiced in Rome that Agricola was poisoned on the Emperor's orders.