Cisalpine Gaul

Cisalpine Gaul (Gallia Cisalpina), also called Gallia Citerior or Gallia Togata, was the part of Italy inhabited by Celts since the 13th century BC. Conquered by the Roman Republic in the 220s BC, it was a Roman province from c. 81 BC until 42 BC, when it was merged into Roman Italy. Until that time, it was considered part of Gaul, precisely that part of Gaul on the "hither side of the Alps" (from the perspective of the Romans), as opposed to Transalpine Gaul ("on the far side of the Alps").

Gallia Cisalpina was further subdivided into Gallia Cispadana and Gallia Transpadana, i.e. its portions south and north of the Po River, respectively. The Roman province of the 1st century BC was bounded on the north and west by the Alps, in the south as far as Placentia by the river Po, and then by the Apennines and the river Rubicon, and in the east by the Adriatic Sea. In 49 BC all inhabitants of Cisalpine Gaul received Roman citizenship, and eventually the province was divided among four of the eleven regions of Italy: Regio VIII Gallia Cispadana, Regio IX Liguria, Regio X Venetia et Histria and Regio XI Gallia Transpadana.

0 (year)

Year zero does not exist in the Anno Domini (or Common Era) system usually used to number years in the Gregorian calendar and in its predecessor, the Julian calendar. In this system, the year 1 BC is followed by AD 1. However, there is a year zero in astronomical year numbering (where it coincides with the Julian year 1 BC) and in ISO 8601:2004 (where it coincides with the Gregorian year 1 BC) as well as in all Buddhist and Hindu calendars.

Historical, astronomical and ISO year numbering systems

Historians

The Anno Domini era was introduced in 525 by Scythian monk Dionysius Exiguus (c. 470–c. 544), who used it to identify the years on his Easter table. He introduced the new era to avoid using the Diocletian era, based on the accession of Roman Emperor Diocletian, as he did not wish to continue the memory of a persecutor of Christians. In the preface to his Easter table, Dionysius stated that the "present year" was "the consulship of Probus Junior [Flavius Anicius Probus Iunior]" which was also 525 years "since the incarnation of our Lord Jesus Christ". How he arrived at that number is unknown.