These 7 points are nicely summarized by Paul Barnett in his volume Is the New Testament Reliable? (IVP Academic, 2003 [second ed.], p. 34). Notably, each fact corroborates the record of the New Testament.
1. Jesus Christ was executed (by crucifixion?) in Judea during the period when Tiberius was emperor (A.D. 14-37) and Pontius Pilate was governor (A.D. 26-36). Tacitus [Annals 15.44.2-5]
2. The movement spread from Judea to Rome. Tacitus [Ibid.]
3. His followers worshipped him as (a) god. Pliny [Letters from Bithynia, c. A.D. 110]
4. He was called “the Christ.” Josephus [Antiquities 20.197-203—an undisputed passage]
5. His followers were called “Christians.” Tacitus, Pliny [see above]
6. They were numerous in Bithynia and Rome. Tacitus, Pliny [see above]
7. His brother was James. Josephus [see above]