The above answers are only partially correct. The Visigoths, otherwise known as the Eastern Goths (as opposed to the Ostrogoths, or Western Goths) were a peaceful farming people who lived in Germany near the Rhine River, the border of the Roman Empire. They maintained a peaceful co-existence with the Romans and Visigothic warriors fought in the Roman army at times. This situation continued until 376 C.E. when the Visigoths were forced from their homeland by the onslaught of the Huns. The Visigoths then asked and received permission to enter the Roman Empire. Upon crossing the Rhine, they were mercilessly victimized by greedy Roman merchants and furnished only meager food supplies, much of which was rotton when it arrived. In desperation, they ultimately revolted. The Eastern Roman Emperor, Valens, led an army against them planning to subdue them. He had planned on assistance from the Western Emperor and his nephew, Valentian. Valentian's army did not arrive, however, and Valen's army was defeated at the battle of Adrianople. Valens was wounded and carried to a nearby farm house. A group of Visigothic warriors, not knowing that the Emperor was inside, set fire to the house, and he died in the flames.
The Visigothic presence in the Empire continued to grow, but was not always turbulent, in fact Visigothic generals often fought in the Roman army against the Huns or other Germanic tribes. The Empire itself, however was soon divided by civil war and competing claimants to the imperial throne. At this point, most Roman generals were Visigoths. In 476 C.E., Orestes, a Roman claimant had his son, Romulus II Augustulus crowned Emperor, even though his son was a feeble minded teenager. Rather than see this charade continue, a Visigothic General, Odoacher, had Orestes killed, forced Romulus to abdicate, and sent the royal robe and crown to Constantinople with a letter informing the Emperor there that he was now the sole Roman Emperor. This action in 476 is considered the end of the Western Roman Empire, one hundred years after the Visigoths first crossed the Rhine.
In 382, Theodosius, Roman ruler at the time, under a treaty made the Visigoths the first independent barbarian nation within the Roman Empire. Visigoths allied with Rome in 394, and Alaric I led the Visigoths in the Roman army against the Huns. Theodosius, before his death, spilt the empire between his sons Honorius and Acradius. The empire was now permanently split into eastern and western empires. In 395, when Theodosius died, the Visigoths relinquished their allegiance with Rome.
If you narrow it down, the visgoths were an East Germanic tribe during 268 A.D. Little is known about them. This Germanic tribe and their closely related "friend" the Ostrogoths created the largest Germanic barbaric group in Early Europe.
The visgoths were once driven out of their homeland by the Romans. But later, after taking refuge in the North of Rome. They made a deadly attack centered at Rome. Now, you must understand that by that time, Rome was already corrupt, wars were bruing inside the once great empire. So when the visgoths saw this, they took advantage and attacked. The vigoths devestated the empire and took many provinces. But they had been defeated. They then retreated to Dacia, a Roman province (which they had conquered a month ago), and established an empire there, which remained untouched until 376.
Tables turned in 376, the visgoths asked the Roman empire to grant them permission to move down south. The request was granted, but when the Roman emperor Valen started ruling, he refused to let the visgoths keep their settelment. When famine struck, the emperor could not deliver the promised supplies. The visgoths, who were peacefull for over 100 years, made a devestating revolt headed at the Roman empire. They once again devestated the empire and also the death of the vicious, traitor emperor.