What is the setting in the novel, The Tain?

The setting of Tain is various provinces of Ireland at some point in the distant past. The conflict is in fact drawn along provincial lines. Ailill and Medb, from the province of Connacht, gather forces from the other three provinces, Munster, Leinster, and Ulster (in Ulster's case, exiles from Ulster), in order to attack Ulster and steal its legendary bull. The story becomes a sort of underdog story, Ulster versus the world.