The Romans found them to be useful mercenaries, and employed them to help fight against the Sassanid Persians.
Around 375CE, the Huns began to press the Goths. Whether this came as a result of westward expansion/migration by the Huns, or as a pushback by the Huns against eastward expansion by the Goths, under their king Ermanaric, is subject to argument. The result was that the Ostrogoths came under Hun rule, and the Huns then began to press on against the Visigoths.
The Visigoth king Fritigern approached the Eastern Roman (Byzantine) Emperor Valens in 376CE, asking to be allowed to settle on the south bank of the Danube. Valens allowed this, but after a famine, the Gothic War of 376-382 ensued, and the Goths and some local Thracians revolted. At the Battle of Adrianople in 378CE, Valens was killed.
Fighting between the Goths and the Romans continued, and a Visigoth army led by Alaric I sacked Rome itself in 410CE. The Visigoths were subsequently allowed to settle in Aquitaine (modern day south-eastern France), where after being driven south by the Franks, they fought and defeated the Vandals, who themselves had been pushed south into modern-day Spain and Portugal. By 475CE, the Goths had conquered most of the Iberian Peninsula, pushing the Vandals further south, into northern Africa. The Visigoth kingdom lasted until 711CE, when it fell into civil war. One faction asked the Muslim Umayyads of North Africa to help, and they decided they wanted to stay., so ended up overrunning the Iberian Peninsular themselves, creating the "kingdom" of Al-Andalus.
In the meantime, the Ostrogothic king Theodemir, broke away from Hunnic rule following the Battle of Nedao in 454, and again decisively defeated the Huns at Bassianae in 468, led by their king Valamir. The Ostrogoths began their conquest of Italy in 488CE, and their kingdom that lasted until 553CE, when Italy returned briefly to Byzantine control, before the Lombards took it over from 568CE.
The Goths were briefly reunited under one king in the early sixth century, when Theodoric "The Great" became regent of the Visigoth kingdom following the death of Alaric II at the Battle of Vouille in 507CE.
(Above) Gothic Nobles escort their king into battle.
The other groups represented in the army - archers, heavy cavalry, skirmishers/scouts armed with javelins, and the warband which formed the basis of the infantry portion of the army. (The javelin men figures are a versatile lot - they also serve part time in my Late Saxon and Viking armies. Slightly later periods, but the figures look close enough to be useable).
