In Germania, written around 98 AD, Tacitus says Suebian men combed the hair back and tied it in a knot behind, and that the fashion marked the free-born off from the enslaved. Nobles wore taller versions to add height and to frighten. He concedes in the same passage that young men of other tribes had taken it up, which is why modern historians will not accept a knot as proof of anyone's ethnicity. The Osterby head is the clearest specimen; the Daetgen man, from the same district, dated 135 to 385 AD, wears one too. A second-century Roman cauldron from a chieftain's grave at Musov in the Czech Republic carries four cast heads, each knotted. A hairstyle travelled. Rome read it as a nation.

Caesar, reporting on 58 BC, treats the Suebi as one tribe in one place between the Rhine and the Elbe, organized into a hundred pagi, each sending a thousand men on campaign every year, strong enough to force their neighbours to leave a belt of empty country around them. Pliny does not use the word as an umbrella at all: for him the Suebi are one of the Irminones. Tacitus, around 100 AD, states plainly that they "are not one single people" — they hold a large part of Germania, "divided into distinct nations and names," and everyone calls them Suebi anyway. He puts their origin with the Semnones on the Elbe, at whose sacred grove "all the people of the same name and blood come together" for rites that included human sacrifice. All of this is Roman testimony about peoples Rome could not reliably name. Herwig Wolfram argued that classical ethnography spread the label so freely it nearly displaced Caesar's own coinage, Germani.

In 58 BC Caesar confronted a king named Ariovistus, who had a Suebian wife and may have been Suebian himself. Invited into Gaul years earlier by the Sequani and already recognized as a king by the Roman senate, he gave Caesar the pretext to draw a line Europe has argued over ever since: Gauls west of the Rhine, Germani east of it, the latter a standing threat to Italy. Caesar beat him, and a hundred pagi of Suebi marching to the Rhine under the brothers Nasuas and Cimberius heard the news and turned back. Half a century later, in 9 BC, Drusus the Elder crushed a Suebian alliance that had sealed itself by crucifying twenty Roman centurions, then sold the survivors into slavery — men and women turned into property to make an example of them. Out of that wreckage came Maroboduus, a Marcomannic royal raised in Rome, who led his people into the Hercynian forest, built a capital at Boiohaemum — the name Bohemia still carries — and drilled his soldiers to near-Roman standard.

The Marcomannic Wars, fought mostly under Marcus Aurelius, began with a raid across the Danube in the 150s or 160s by the Suebian Langobardi. Ballomarius, king of the Marcomanni, and ten other envoys took a peace mission to the governor of Pannonia; oaths were sworn and everyone went home. They did not hold. The Marcomanni and Quadi crossed the river into Italy itself, destroying Opitergium (modern Oderzo) and besieging Aquileia. Marcus Aurelius set up headquarters at Carnuntum. Between 172 and 174 a Roman force came close to annihilation against the Quadi until a sudden rainstorm turned the day — an episode carved onto the Column of Marcus Aurelius. The war destroyed the old frontier order. Within a generation new names appear: Alemanni, first recorded when Caracalla fought them in 213; Juthungi, described on a monument of 260 near Augsburg as Semnones from the Elbe. Rome gave up the Agri Decumates; the Alemanni took the country that became medieval Swabia, which still wears a version of the Suebian name.

Around 406 large numbers of Middle Danubians, Quadi prominent among them, crossed into Gaul; by 409 a force calling itself Suebi was in Hispania alongside Vandals and Alans, dividing the peninsula by agreement with the rebel Roman general Gerontius. Rome repudiated the deal and set the Visigoths on it. The Suebi outlasted everyone. From Braga, in Gallaecia — now Galicia and northern Portugal — Hermeric consolidated the province from about 409 to 438; Rechila pushed south; Rechiar, ruling from 448, became the first Germanic king to profess Nicene Christianity and the first to mint coins in his own name, before losing to the Visigothic king Theodoric II at the Orbigo in 456. From 456 or 457 the kingdom was a Visigothic vassal, and lasted like that for over a century: Martin of Braga drove its conversion to Catholicism, Ariamir called the First Council of Braga in 561, Miro the second in 572. Leovigild annexed it in 585. The kingdom ended. The place-names did not.