Short answers, pulled from the story.
The name Bituriges Cubi derives from the Gaulish Biturīges, meaning "kings of the world" or possibly "perpetual kings." The stem bitu- meant "world" or "perpetual" and riges meant "kings"; Cubi distinguished this group from the homonym tribe, the Bituriges Vivisci, who lived in the Bordelais region.
The Bituriges Cubi lived in the territory corresponding to the later French province of Berry, in central France. Their chief town was the oppidum of Avaricum Biturigum, which corresponds to the modern city of Bourges.
Ambigatus was a legendary king of the Bituriges Cubi who, according to the historian Livy, ruled a Gaul so prosperous that its population could hardly be governed. Facing overpopulation, he sent his sister's sons Bellovesus and Segovesus to settle new territories; Bellovesus is credited in the legend with leading the Gallic invasion of northern Italy.
The Bituriges Cubi supported the Arverni and Vercingetorix against Julius Caesar during the Gallic Wars. Their oppida of Noviodunum and Avaricum were besieged in 52 BC, and they contributed fighters to the defense of Alesia. After Vercingetorix's defeat, Rome suppressed a further revolt in Biturigian territory in 51 BC before the tribe submitted quickly.
The official motto of Bourges is the Latin phrase summa imperii penes Biturges, meaning "all the power in the hands of the Bituriges," drawn from a passage in Livy's history of Rome. The city's name itself derives from the Bituriges tribe, as does the regional name Berry.
Greek ceramics and amphoras imported from Massalia, along with locally made fine pottery dated to the second half of the sixth century BC, have been found at the Bourges site. Historian Venceslas Kruta has argued these finds give "archaeological credit to the essence of the tradition reported by Livy" about the Bituriges' regional prominence.