Year 198 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Catus and Flamininus (or, less frequently, year 556 Ab urbe condita). The denomination 198 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Following the defeat of the Han at the hands of the Xiongnu at Baideng in 200 BC, courtier Liu Jing (劉敬) is dispatched by Han emperor Gaozu for negotiations. The peace settlement eventually reached between the parties includes a Han princess given in marriage to the chanyu (called heqin 和親 or "harmonious kinship"); periodic tribute of silk, liquor and rice to the Xiongnu; equal status between the states; and the Great Wall as mutual border. This treaty sets the pattern for relations between the Han and the Xiongnu for some sixty years.