One of the two main divisions of the Goths, the Visigoths migrated into the Roman Empire in 376 AD, sacked Rome in 410 AD and settled in southern Gaul and Spain.
Like their tribal cousins, the Ostrogoths, they trace their origins to the ancient Gothic homelands in Scandinavia and northern Poland. The Goths migrated south along the rivers of central Europe in the Second Century and some settled on the steppes north of the Black Sea while others settled in the forests north of the lower Danube. It was these "Tervingians" or 'forest dwellers' who later formed the core of the Visigoths.
When the Huns destroyed the kingdom of their steppe-dwelling cousins to the east and then attacked them, many of these Tervingian Goths sought refuge in the Eastern Roman Empire in 376 AD. Mistreated by the Roman authorities, the Goths rebelled and rampaged through Thrace, meeting and defeating the Emperor Valens in the great battle of Adrianople in August 378 AD.
These Visigoths - the people who formed out of the Tervingian refugees and their allies - reached a settlement with the Emperor Theodosius in 380 and became federate allies of Rome. But on his death they went on the rampage again and eventually, led by their king Alaric, invaded Italy. After a drawn out cat-and-mouse war with the Roman-Vandal general Stilicho, they sacked Rome in 410 AD and then tried to cross to north Africa. Alaric died soon afterwards and his successor, Athaulf, led his people into southern Gaul where they set up a kingdom based around Toulouse.
The Visigoths were a major power in Gaul and Spain for many years, allying with Rome against Attila in 451 AD and working as partners with their Ostrogothic cousins in Italy from 493 AD. But in 507 AD most of the Visigothic kingdom in Gaul was conquered by Clovis the Frank and the Visigoths fell back into their Spanish territory.
The Visigothic kingdom of Spain lasted for another 200 years, until in 711 King Roderic was defeated by Tarik and an army of Islamic Berber warriors. The remants of the Visigoths and their Hispano-Roman supporters were driven into northern Spain, where they established several smaller kingdoms and and began the centuries of war with the Muslims of "Al-Andalus" which eventually led to the final reconquest of Spain in 1492 AD.
Jordanes - The Origin and Deeds of the Goths
Catholic Encyclopaedia - The Visigoths
Timeline of the Visigothic Kings
Sidonius Apollinaris: Description of King Theodoric of the Visigoths, c. 460
The Visigoths in Spain