Short answers, pulled from the story.
The Old Saxons, also called Continental Saxons, were a Germanic people of early medieval Saxony in what is now northern Germany. Their territory, which became a Carolingian stem duchy in 804, covered Westphalia, Eastphalia, Angria, and Nordalbingia, roughly equivalent to Holstein and the southern part of modern Schleswig-Holstein.
The name Saxon is traditionally said to derive from the seax, a type of single-edged knife called seax in Old English and sahs in Old High German. The term was first used in Roman records to describe seaborne raiders attacking the empire from north of the Rhine, applied broadly to any groups arriving by boat, much like the later term Viking.
Charlemagne fought the Saxon Wars from 772 to 804, a series of annual campaigns that ended with the Saxons' forced conversion to Christianity and annexation into the Frankish empire. He destroyed their sacred pillar Irminsul at Eresburg in 772 and deported 10,000 Nordalbingian Saxons to Neustria, giving their lands in Wagria to the Abotrites.
Saxon society below its leaders was divided into three hereditary castes: the edhilingui (warrior nobility), the frilingi (freemen), and the lazzi (descendants of conquered peoples). The Lex Saxonum set their wergilds at 1,440 solidi for an edhilingui, six times that of a frilingi and eight times that of a lazzi, and forbade intermarriage between castes.
The Saxons spoke Old Saxon, first clearly attested in the 8th century after Charlemagne's conquest. It evolved into Middle Low German around 1200 and then modern Low German around 1500, which became the lingua franca of the Hanseatic League before declining in favour of Dutch and German.
Because Saxons were among the dominant Germanic settlers of Britain, Celtic-speaking peoples applied their forms of Saxones to the English: Sasannach in Scottish Gaelic, Sasanach in Irish, Saeson in Welsh, and Sawsnek in Cornish. Finnish and Estonian later extended the same root to mean Germany and Germans as a whole, and the Finnish word sakset (scissors) preserves the name of the seax knife from which Saxon is derived.