2000 years ago the Baltic Sea was known to the Romans as the Mare Suebicum. Partially because of his unfamiliarity with the various Germanic peoples interacting with Rome at the time, the historian Tacitus referred to all eastern Germanic people as Suebi. More recent scholarship has shown that view to be an oversimplification. The Suebi eventually migrated south and west to reside for a while in the area of modern Germany, where their name survives in the historic region known as Swabia.
Closely related to the Alamanni and often working in concert with them, the Suebi for the most part stayed on the "German" side of the Rhine until December 31, 406, when much of the tribe joined the Vandals and Alans in breaching the Roman frontier at Mainz, thus launching an invasion of the province of Gaul.
While the Vandals and Alans clashed with the Roman-allied Franks for supremacy in Gaul, the Suebi worked their way to the south, eventually crossing the Pyrenees Mountains and entering Spain. In 409, their king Hermeric established his people in territories making up the northwestern part of the Iberian peninsula, and eventually received official recognition from the Romans for their settlement there.
The Suebic kingdom in Spain lasted for 175 years after that, and seems to have enjoyed relatively stable government for most of that time. There were occasional clashes with the Visigoths, who arrived in Spain in 416 and came to dominate most of the peninsula, but the Suevi maintained their independence until 584, when the Visigothic King Leovigild invaded the Suevi kingdom and finally defeated it. Andeca, the final king of the Suevi, held out for a year before surrendering in 585. With his surrender, this branch of the Suevi vanished into the Visigothic kingdom.
The Suebi who remained behind in 406 soon lost their identity to the Alamanni and were absorbed into that tribe, although the land they occupied preserves their name.