Year 99 (XCIX) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Palma and Senecio (or, less frequently, year 852 Ab urbe condita). The denomination 99 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- Emperor Trajan returns to Rome from an inspection of the Roman legions along the Rhine and Danube frontiers.
- Emissaries of the Kushan Empire reach Emperor Trajan.
- Richimerus I fights a battle with a combined army of Romans and Gauls at Basana near Aachen.