Here’s what Encyclopedia Britannica has to say about Pompei:

It seems certain that Pompeii, Herculaneum, and nearby towns were first settled by Oscan-speaking descendants of the Neolithic inhabitants of Campania. Archaeological evidence indicates that the Oscan village of Pompeii, strategically located near the mouth of the Sarnus River, soon came under the influence of the cultured Greeks who had settled across the bay in the 8th century bce. Greek influence was challenged, however, when the Etruscans came into Campania in the 7th century. The Etruscans’ influence remained strong until their sea power was destroyed by King Hieron I of Syracuse in a naval battle off Cumae in 474 bce. A second period of Greek hegemony followed. Then, toward the end of the 5th century, the warlike Samnites, an Italic tribe, conquered Campania, and Pompeii, Herculaneum, and Stabiae became Samnite towns.

Pompeii is first mentioned in history in 310 bce, when, during the Second Samnite War, a Roman fleet landed at the Sarnus port of Pompeii and from there made an unsuccessful attack on the neighbouring city of Nuceria. At the end of the Samnite wars, Campania became a part of the Roman confederation, and the cities became “allies” of Rome. But they were not completely subjugated and Romanized until the time of the Social War. Pompeii joined the Italians in their revolt against Rome in this war and was besieged by the Roman general Lucius Cornelius Sulla in 89 bce. After the war, Pompeii, along with the rest of Italy south of the Po River, received Roman citizenship. However, as a punishment for Pompeii’s part in the war, a colony of Roman veterans was established there under Publius Sulla, the nephew of the Roman general. Latin replaced Oscan as the official language, and the city soon became Romanized in institutions, architecture, and culture.

Mount Vesuvius erupted on August 24, 79 ce. A vivid eyewitness report is preserved in two letters written by Pliny the Younger to the historian Tacitus, who had inquired about the death of Pliny the Elder, commander of the Roman fleet at Misenum. Pliny the Elder had rushed from Misenum to help the stricken population and to get a close view of the volcanic phenomena, and he died at Stabiae. Site excavations and volcanological studies, notably in the late 20th century, have brought out further details. Just after midday on August 24, fragments of ash, pumice, and other volcanic debris began pouring down on Pompeii, quickly covering the city to a depth of more than 9 feet (3 metres) and causing the roofs of many houses to fall in. Surges of pyroclastic material and heated gas, known as nuées ardentes, reached the city walls on the morning of August 25 and soon asphyxiated those residents who had not been killed by falling debris. Additional pyroclastic flows and rains of ash followed, adding at least another 9 feet of debris and preserving in a pall of ash the bodies of the inhabitants who perished while taking shelter in their houses or trying to escape toward the coast or by the roads leading to Stabiae or Nuceria. Thus Pompeii remained buried under a layer of pumice stones and ash 19 to 23 feet (6 to 7 metres) deep. The city’s sudden burial served to protect it for the next 17 centuries from vandalism, looting, and the destructive effects of climate and weather.