Short answers, pulled from the story.
The Germanic peoples were tribal groups who lived in Northern Europe during classical antiquity and the early Middle Ages. Their territory, called Germania by Roman writers, stretched east of the Rhine to southern Scandinavia and the Vistula in the east, with the upper Danube as a southern border. Some Germanic-speaking peoples, such as the Bastarnae and Goths, lived further east in what is now Moldova and Ukraine.
The etymology of the Latin word Germani, from which Germanic derives, is unknown and scholars dispute even the language it came from, with proposals including Germanic, Celtic, Latin, and Illyrian origins. The historian Wolfgang Pfeifer suggests the name is likely of Celtic etymology, possibly related to the Old Irish word gair meaning "neighbours" or the Celtic word gairm meaning war cries. The name was transmitted to the Romans through Celtic speakers.
The Battle of the Teutoburg Forest in 9 CE was an ambush in northern Germany in which Arminius of the Cherusci destroyed the three legions of Publius Quinctilius Varus. The defeat persuaded Rome to abandon the permanent integration of Germania into the empire. In his will, read aloud by Tiberius, Augustus recommended expanding the empire no further than the Rhine-Danube frontier.
The Visigoths were the first Germanic people to convert to Christianity, adopting Arian Christianity at the latest in 376 CE, aided by the bishop Wulfila who had translated the Bible into Gothic around 350-380 CE. The Frankish king Clovis I converted to Nicene Christianity in 496. The Saxons were forcibly converted by Charlemagne following their conquest in the Saxon Wars in 776/777. The last Germanic people to convert were the Swedes, and the pagan Temple at Uppsala appears to have continued to exist into the early 1100s.
Runes are a native script developed by Germanic speakers, with the earliest form, the Elder Futhark, consisting of 24 characters. Estimates for when the alphabet was created range from 100 BCE to 100 CE, and generally accepted inscriptions in the Elder Futhark date from 200 to 700 CE. The word rune descends from Proto-Germanic runa, meaning primarily "secret", and unlike similar indigenous European scripts the runes were not replaced by the Latin alphabet before the 1st century BCE.
Scholars have increasingly questioned whether a shared Germanic ethnic identity ever existed, with the Toronto School around Walter Goffart arguing that ideas about Germanic culture were taken from later epochs and projected back onto antiquity. The term was also co-opted by the Nazi movement, producing a scholarly backlash in the second half of the 20th century. Most historians and archaeologists researching late antiquity and the early Middle Ages have moved away from the term since 1990, though linguists often retain it as a long-established convenient label.