Answer
Tacitus was a Roman historian who received letters from Pliny the Younger, a renowned Roman author and politician. These letters provide valuable insights into the political and social climate of ancient Rome during the late 1st and early 2nd centuries AD. Tacitus used Pliny's letters as sources for his historical works, particularly his Annals and Histories, which chronicle the reigns of the Roman emperors from Tiberius to Domitian.